Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
1
192.168.1.144
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
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Sankt Lorenzen 36, 8715, Sankt Lorenzen, Austria
Mechanics, Materials Science & Engineering Journal
July 2017
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
3
Mechanics, Materials Sciences & Engineering Journal, Austria, Sankt Lorenzen, 2017
Mechanics, Materials Science & Engineering Journal (MMSE Journal) is journal that deals in peer-
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The Journal Policy declares the acceptance of the scientific papers worldwide, if they passed the
peer-review procedure. Published by industrial company Magnolithe GmbH
Editor-in-Chief Mr. Peter Zisser
Dr. Zheng Li, University of Bridgeport, USA
Prof. Kravets Victor, National Mining Univerisity, Ukraine
Ph.D., Girish Mukundrao Joshi, VIT University, India
Dr. Yang Yu, University of Technology Sydney, Australia
Prof. Amelia Carolina Sparavigna, Politecnico di Torino, Italy
ISSN 2412-5954
e-ISSN 2414-6935
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Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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4
CONTENT
I. Materials Science MMSE Journal Vol. 11 ................................................................................... 5
Microcapillary Features in Silicon Alloyed High-Strength Cast Iron. R.K. Hasanli,
S.N. Namazov ...................................................................................................................................... 7
Characterization of Aluminium Alloy AA2219 Reinforced with Graphite by Stir Casting
Method. V. Bhuvaneswari, G. Yuvaraj, Dr. A. Saravanakumar, L. Rajesh Kumar, R. Kiruthiha ... 11
Process Optimization of Warm Laser Shock Peening without Coating for Automotive Spring
Steel. S. Prabhakaran, S. Kalainathan ............................................................................................. 18
Studies on 1-Butyl 3-Methylimidazolium Hexafluorophosphate Incorporated PVC-PBMA
Polymer Electrolytes. R. Arunkumar, Ravi Shanker Babu, M. Usha Rani ..................................... 22
Conductivity Enhancement Studies on Poly (Acrylonitrile)-Poly (Vinylidene Fluoride)
Composite Polymer Electrolytes. M. Usha Rani, Ravi Shanker Babu, S. Rajendran,
R. Arunkumar .................................................................................................................................... 28
A Comparative Study on the Dielectric Properties of Lanthanum Copper Titanium Dioxide
(La
2
/3Cu
3
Ti
4
O
12
) Ceramic with Conventional and Microwave Sintering Routes. Surya Mallick,
Pawan Kumar, M. Malathi ............................................................................................................... 34
Theoretical Investigation on the Structural, Elastic and Mechanical Properties of
Rh3HxNb1-x(x=0.125, 0.875). M. Manjula1, M. Sundareswari ..................................................... 39
Synthesis and Characterization of Monolithic ZnO-SiO
2
Nanocomposite Xerogels.
D. Prasanna, P. Elangovan, R. Sheelarani ...................................................................................... 44
DC Conductivity and Dielectric Studies on Fe Concentration Doped LiIAgIB
2
O
3
Glasses.
K. Sreelatha, K. Showrilu, V. Ramesh .............................................................................................. 49
Conductivity, Morphology and Thermal Studies of Polyvinyl Chloride (PVC)-Lithium
Nitrate with Cadmium Oxide (CdO). P. Karthika, R. Gomathy, P.S. Devi Prasadh ................... 55
Electrochemical Detection of Ascorbic Acid Using Pre-treated Graphite Electrode Modified
with PAMAM Dendrimer with Poly (Nile Blue). C. Lakshmi Devi, J. Jayadevi Manoranjitham,
S. Sriman Narayanan ........................................................................................................................ 60
Morphological Investigation of Small Molecule Solution Processed Polymer Solar Cells
Based on Spin Coating Technique. Liyakath Reshma, Kannappan Santhakumar ........................ 65
Analysis on Spectroscopic and Dielectric Study of PBS/PVA Polymer Nanocomposite via
Facile Hydrothermal Process. S. Sharon Tamil Selvi, J. Mary Linet ............................................. 70
Voltammetric Sensing of Dopamine at a Glassy Carbon Electrode Modified with Chromium
(III) Schiff Base Complex. K. Bharathi, S. Praveen Kumar, P. Supriya Prasab, V. Narayanan ... 76
Mechanical and Morphological Characterization of PVA/SA/HNTs Blends and Its
Composites. N. Thayumanavan ........................................................................................................ 81
Mechanical and Thermal Behaviour of Hybrid Filler Reinforced PP/ABS Blend.
S.M.D. Mastan Saheb, P. Tambe, M. Malathi .................................................................................. 86
Effect of Multiple Laser Shock Peening on the Mechanical Properties of ETP Copper. Ayush
Bhattacharya, Siddharth Madan, Chirag Dashora, S. Prabhakaran, V.K. Manupati, S. Kalainathan,
K.P.K. Chakravarthi ......................................................................................................................... 91
Determination of Uric Acid with the Aid of N, N'-Bis (Salicylaldimine)-Benzene-1, 2-Diamine
Cobalt (II) Schiff Base Complex Modified GCE. G.B. Hemalatha, S. Praveen Kumar, S.
Munusamy, S. Muthamizh, A. Padmanaban, T. Dhanasekaran, G. Gnanamoorthy,
V. Narayanan .................................................................................................................................... 97
Electron Distribution in BaTi0.98Zr0.02O
3
Piezoceramic Using X-ray Structure Factors.
J. Mangaiyarkkarasi, S.Sasikumar, R. Saravanan .......................................................................... 102
Synthesis, Structural and Optical Studies of Yb Doped CuGaS
2
Thin Films Prepared By
Facile Chemical Spray Pyrolysis Technique. S. Kalainathan, N. Ahsan, T. Hoshii, Y. Okada,
T.Logu, K. Sethuraman ................................................................................................................... 110
Performance of SiO
2
- TiO
2
Thin Films as Protective Layer to Chlorophyll in Medicinal
Plants from UV Radiation: Influence of Dipping Cycles. M. Sankareswari, B. Karunai Selvi,
K. Neyvasagam ................................................................................................................................ 118
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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5
Structural and Optical Properties of DC Magnetron Sputtered Zirconium Titanate Thin
Films of Varied Film Thickness. D. Jhansi Rani, A. Guru Sampath Kumar, T. Subba Rao ....... 124
Effect of Additives on the Performance of Non-Fullerene Based Organic Solar Cells in Non-
Halogenated Solvents. L. Reshma, V. Sai Saraswathi, P. Induja, M. Shivashankar,
K. Santhakumar ............................................................................................................................... 128
Characterization, Design and Optimization of Industrial Phosphoric Acid Production
Processes by Artificial Neural Network. Gholamhosseion Grivani, Shahriyar Ghammamy, Farzane
Yousefi, Mehdi Ghammamy ............................................................................................................ 133
Microstructure and Supercapacitor Properties of V
2
O
5
Thin Film Prepared by Thermal
Evaporation Method. M. Dhananjaya, N. Guru Prakash, G. Lakshmi Sandhya,
A. Lakshmi Narayana, O.M. Hussain ............................................................................................. 140
Effect of Substrate Temperature on Microstructural and Optical Properties of
Nanostructured ZnTe Thin Films Using Electron Beam Evaporation Technique. M. Shobana,
N. Madhusudhana Rao, S. Kaleemulla, M. Rigana Begam, M. Kuppan ........................................ 147
Textural Enhancement of Hydrothermally Grown TiO
2
Nanoparticles and Bilayer-
Nanorods for Better Optical Transport. J. Sahaya Selva Mary, V. Chandrakala, Neena Bachan,
P. Naveen Kumar, K. Pugazhendhi, J. Merline Shyla ..................................................................... 153
Novel and Proficient Organic-Inorganic Lead Bromide Perovskite for Solid-State Solar
Cells. B. Praveen, Tenzin Tenkyong, W. Jothi Jeyarani, J. Sahaya Selva Mary, V.Chandrakala,
Neena Bachan, J. Merline Shyla ..................................................................................................... 160
Stress Stability of Aluminium-Glass Composites. Abodunrin O.W., Alo F.I. ........................ 167
On the Rogue Wave Solution of the Davey-Stewartson Equation. D. Prasanna, S. Selvakumar,
Dr. P. Elangovan ............................................................................................................................ 174
Growth and Characterization of Potassium Di Chromate Doped L-Alanine Crystal.
D. Prasanna, N.Karthikeyan, Dr. P. Elangovan.............................................................................. 180
II. Mechanical Engineering & Physics MMSE Journal Vol. 11 ............................................... 186
Vibration Optimization of a Two-Link Flexible Manipulator with Optimal Input Torques.
Hadi Asadi, Milad Pouya, Pooyan Vahidi Pashaki ........................................................................ 187
Design and Simulation of Capacitive Type Comb-Drive Accelerometer TO Detect Heart Beat
Frequency. P. Ashok Kumar1, G.K.S. Prakash Raaju1, K. Srinivasa Rao ................................... 199
Particular Issues Associated with Performing Meterage Through the Use of Magneto
Therapy Devices. Y.S. Lapchenko, V.Y. Denysiuk, V.V. Krasovski, V.P. Symonyuk ..................... 207
Numerical Simulation of the Shear Resistence Test Proposed by NBR 7190 (1997) for a Wood
of Corymbia Citriodora. Luciano Rossi Bilesky, Claudio De Conti, Priscila Roel de Deus ....... 215
The Influence of Biofuel on the Operational Characteristics of Small Experimental Jet
Engine. K. Ratkovska, M. Hocko, J. Cernan, M. Cuttova .............................................................. 229
Static Analysis of Total Knee Joint Replacement. Vinay Kumar. P, S. Nagakalyan ............ 238
Applying Calculations of Quaternionic Matrices for Formation of the Tables of Directional
Cosines. Victor Kravets, Tamila Kravets, Olexiy Burov ................................................................ 248
Seismic Behaviour of Eccentrically Braced Frame with Vertical Link. Vahid Osat, Ehsan
Darvishan, Morteza Ashoori ........................................................................................................... 260
VII. Environmental Safety MMSE Journal Vol. 11 ................................................................... 269
Understanding the Nature and Characteristics of Dark-Black Stains on Rooftops in Uyo
Metropolis-Nigeria. Ihom A.P., Uko D.K., Markson I.E., Eleghasim O.C. ................................... 270
Prospects to Use Biogas of Refuse Dams of Dnipropetrovsk Region (Ukraine) as Alternative
Energy Carrier. Ye.A. Koroviaka, V.O. Rastsvietaiev, O.O. Dmytruk, V.V. Tykhonenko ............ 289
VI. Information Technologies MMSE Journal Vol. 11 ............................................................. 298
Random Sparse Sampling and Equal Intervals Bregman High-Resolution Signal
Reconstruction. Guojun Qin, Jingfang Wang ............................................................................... 299
VII. Economics & Management MMSE Journal Vol. 11 .......................................................... 308
Methodology of Assessing the Impact of Urban Development Value of the Territory on the
Value of Residential Real Estate by Example of Kiev City, Ukraine. I.M. Ciobanu ............... 309
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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I. M a t e r i a l s S c i e n c e
M M S E J o u r n a l V o l . 1 1
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
7
Microcapillary Features in Silicon Alloyed High-Strength Cast Iron
R.K. Hasanli
1,a
, S.N. Namazov
2,b
1 Associated professor, Dr., Azerbaijan Technical University, Baku, Azerbaijan
2 Professor, Dr., Azerbaijan Technical University, Baku, Azerbaijan
a hasanli_dr@mail.ru
b subhan_namazov@daad-alumni.de
DOI 10.2412/mmse.89.99.501 provided by Seo4U.link
Keywords: alloyed, high-strength cast iron, metal form, segregation, structure.
ABSTRACT. Present study explores features of silicon micro capillary in alloyed high-strength cast iron with nodular
graphite (ductile iron) produced in metal molds. It identified the nature and mechanism of micro liquation of silicon in a
ductile iron alloyed with Nickel and copper, and demonstrated significant change of structural-quality characteristics. It
was concluded that the matrix of alloyed ductile iron has a heterogeneous structure with cross reinforcement and high-
silicon excrement areas.
Introduction. High quality of iron castings depends largely on the structure and properties, including
the nature of the distribution of silicon. However, the structure of high-strength cast iron with nodular
graphite (ductile iron) produced in the metallic form, and the nature of silicon micro liquation in it
has not been studied. Therefore, research in this direction represents both scientific and practical
interest.
Analyses of the Microcapillary Features in Silicon Alloyed High-Strength Cast Irons. Method of
etching in an alkaline solution of sodium picrate was used to study microrespirometry of silicon in
cast iron. The study of micro liquation of silicon in ductile iron, cast in the mold, showed that there
is a significant difference from micro liquation in ductile iron, cast in sand form. Analysis of ductile
iron chill in the cast state showed that the iron acquires the structure of a white cast iron consisting of
perlite and ledeburite (Fig.1).
Fig. 1. The microstructure of unalloyed ductile iron, x300.
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
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Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
8
Ductile iron, cast in the mold, unalloyed Nickel and copper are significantly different from unalloyed,
cast in the mold (Fig.2). Introduction of iron Nickel in an amount of from 1.0 to 2.0% increases the
chill cast iron and refines eutectic grains (Fig.3).
Fig. 2. The microstructure of ductile iron, alloyed with 1.0% Ni and 0.5% Cu, x300.
Fig. 3. The microstructure of ductile iron, alloyed with 1.0% Ni, x300.
It is established that the characteristic distribution of silicon in the alloy, chill cast irons due to their
cast structure and has a stable character which does not change after annealing, normalizing and
tempering. The area of metal, representing annealing of cementite, retains their chemical composition
with low content of silicon. It was determined that the copper and Nickel with temperatures of
crystallization increase the activity of carbon (like silicon) and therefore increase its distribution in
the crystal lattice of iron.
The distribution of silicon in the Nickel-copper cast irons, cast into the metal mold and sand mold,
close to equilibrium. Only a small region along the boundaries of austenitic grains has a lower content
of silicon. However, in this case, the contrast in the color of the cone is negligible.
In the Nickel-irons non-uniform distribution of silicon was observed, a reflective cast of austenite -
ledeburite structure. The size of the striped areas (concentration of Si) decreases with increasing
Nickel content in the alloy. However, such heterogeneity does not cause deterioration of properties
that would be expected in accordance with existing views on the impact of micro liquation silicon on
notch toughness (COP) at low temperatures.
It is found that in chill alloyed and unalloyed cast iron with partial chill the most enriched silicon are
at the boundaries of the areas occupied by stable and metastable eutectics. The high concentration of
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9
silicon is observed between colonies of plastic ledeburite. Graphite is observed around the highest
concentration of this element.
Unlike half-iron, with the cross-cutting chill, silicon is concentrated mainly in high-silica areas,
namely between the eutectic colonies in complex eutectics, one of the phases in which the
silicocarbide (BCC) or carbide in eutectoid (C+SC), acanthophyllum cementite. In primary and
eutectic austenite (pearlite) content of silicon is lowered.
In works [1], [2], [3], [4], [5] it was proposed that the annealing leads to equalization of chemical
composition upon exposure of the alloy in the austenite region. However, there is another point of
view according to which crystallization occurred when the heterogeneity of the chemical composition
is very stable and fundamentally cannot be eliminated by heat treatment and, in particular, annealing
[6], [7], [8], [9].
When etching of annealed cast iron in picrate of sodium, we found a very peculiar picture of micro
capillary silicon. There is a clear alternation of the areas enriched and depleted in silica, the first of
which are arranged around graphite inclusions, the second - in places where before annealing the
cementite existed.
Mutual arrangement, configuration and size of the combined silicon regions coincide with the
location and shape of the plates of cementite or ledeburite colonies. At the edges of the casting is
observed banded pattern characteristic of directional solidification, and in the center - homogeneous
composition of the zone close to equated.
Thus, it is established that during annealing there is a redistribution of silicon and this is the most
enriched region adjacent to the graphite. However, it is clear that the redistribution occurs only within
a former permitting (austenitic crystallization) regions.
In the locations of the eutectic of cementite, the content of silicon is reduced and after austenitization
of the metal substrate, as well as the final thermal treatment normalization. This result is consistent
with the view stating that when crystallization occurs chemical polarization, caused by different
affinity of the elements to carbon [10], [11], [12].
It is established that carbide-forming elements (Mn, etc.) during the crystallization of the concentrate
in the cementite promote graphitization (Si, Ni, Cu, etc.) in the austenite and this polarization is very
stable. Given the suggested it can be argued that the revealed micro liquation in the picture reflects
an inhomogeneous distribution of not only silicon, but also other elements.
Thus, high-strength cast iron can be considered as a composite material having a heterogeneous
structure with a cross reinforcement consisting of alternating high-silicon regions having a high
hardness and brittleness, and almost excrement, more plastic granules, probably doped with
manganese. Such arrangement of the matrix and reinforcing phases in combination with the presence
of solid lubricants graphite meets the Sharpie rule and may be one of the prospective directions in
creation of wear-resistant cast iron with a heterogeneous structure.
Detected feature in the distribution of silicon can certainly affect the Mechanical properties of
the material. It was established that higher mechanical properties are observed at full, or a significant
chill (exceeding 50%) alloyed cast irons in the cast state. During subsequent thermal treatments
bleached and half-alloy cast irons are mainly pearlite structure with spheroidal graphite.
This structure iron is the most desirable to improve its properties. In addition, the size of the
homogeneous micro regions and graphite inclusions with the increase in the rate of supercoiling of
the alloy crystallizing decreases, which also positively affects the properties of cast iron.
All this makes it possible to express an opinion of the relative influence of micro heterogeneity of
chemical composition on the properties of cast iron. Meanwhile, the generally accepted view that
segregation in cast iron is undesirable as it decreases the ductility of the material. Moreover, even
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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10
after annealing to achieve complete homogeneity of the cast iron chemical composition is not
possible.
Therefore, in our opinion, one should strive to create such a structure of iron, in which a homogeneous
chemical composition in micro-area would be very fine and brittle and ductile zones efficiently
combined, forming a relatively micro heterogeneous structure. Such a picture is obtained by chill
casting magnesium cast irons subjected to annealing, which increases their properties compared with
the cast irons of similar composition, obtained by casting in sand mold.
Summary. The study of the processes of structure formation in ductile iron casting in the mold
confirms the accuracy of the choice of complex dopants, in an amount of 1.0% Ni and 0.5% Cu that
are responsible for the development of cast metal parts applied in conditions of friction, wear and
elevated mechanical loads. These working conditions are typical for parts of oilfield equipment.
Based on the research of micro capillary silicon and other alloying elements it was proposed that
ductile iron can be considered as a composite material having a heterogeneous structure with
alternation of regions with different silicon content.
References
[1] I.P. Bunin, Y.N. Malinochka, B.P. Taran. Fundamentals of metallography of cast iron. Moscow,
Metallurgy, 1998, 413 p.
[2] V.A. Ilyinsky, A.A. Zhukov and others. New in the theory of graphitization. The relationship
between primary and secondary crystallization graffitists iron-carbon alloys // Metallography and
heat treatment of metals, 2001, No.10. P.10-16
[3] High-strength cast iron with nodular graphite. Theory, production technology, properties and
applications / ed. by M.V. Voloshchenko. Kiev: Sciences. Dumka, 2004, 203 p.
[4] R.K. Hasanli. Structure and properties of ductile iron. Baku, Science, 2013, 252 p.
[5] R.K. Hasanli Peculiarities of structure and phase composition of heat-treated high-strength cast
irons with nodular graphite // Journal of mechanical engineering, 2013, No. 10, pp. 31-33
[6] A.I. Belyakov and others. Production of castings from high-strength nodular cast iron. M.,
Mechanical Engineering, 2010, p. 712
[7] R.K.Hasanli. High-strength cast iron with nodular graphite. Baku: Science, 1998, 203 p.
[8] V.V. Dubrov and others, The use of high-strength cast iron in valve. In proc. High-strength cast
iron with nodular graphite. Kiyev, Naukova Dumka, 1998, pp. 78-81.
[9] E.A. Silva, L.F.V.M. Fernandes, N.A.S. Sampaio, R.B. Ribeiro, J.W.J. Silva, M.S.Pereira (2016),
A Comparison between Dual Phase Steel and Interstitial Free Steel Due To the Springback Effect.
Mechanics, Materials Science & Engineering Journal Vol.4, Magnolithe GmbH, DOI:
10.13140/RG.2.1.3749.7205
[10] L. I. Éfron, D. A. Litvinenko (1994), Obtaining high-strength weldable steels with bainite
structure using thermomechanical treatment, Metal Science and Heat Treatment, Vol. 36, Is. 10,
Springer, DOI 10.1007/BF01398082
[11] I.N. Bogachev, R.I. Mints Cavitation-erosion fracture of cast iron. Sat. Theory and practice of
foundry production, Ural Polytechnic Institute, vol. 89, 1999, pp. 71-78.
[12] L.P. Ushakov Wear-resistant cast iron with spheroidal graphite. M., Mechanical engineering,
2005, 153 p., DOI 10.1007/BF01398082
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
11
Characterization of Aluminium Alloy AA2219 Reinforced with Graphite by Stir
Casting Method
V. Bhuvaneswari¹
, a
, G. Yuvara
, b
, Dr. A. Saravanakumar¹
, c
, L. Rajesh Kumar¹
, d
, R. Kiruthiha¹
, e
1 KPR Institute of Engineering & Technology, Coimbatore, India
a bhuvaneswari.v@kpriet.ac.in
b yuvarajg75@gmail.com
c saravanakumar.a@kpriet.ac.in
d
l.rajeshkumar@kpriet.ac.in
e rkiruthu@gmail.com
DOI 10.2412/mmse.79.48.932 provided by Seo4U.link
Keywords: aluminium alloy, graphite, mechanical properties, stir casting method.
ABSTRACT. Aluminium alloy has been accepted in the world wide for the fabrication of lightweight structures requiring
a high strength to weight ratio, such as aerospace, automotive and structural components resulting in savings of materials
and energy. In this work, mechanical properties like porosity test and surface roughness test of Aluminium Alloy AA2219
is reinforced with graphite powder in the ratio of 1%, 3%, 4.5% (in terms of weight) was done. It is fabricated with
different composition of graphite using stir casting method and maintained at the temperature of 1023 K, and running
speed at 500 rpm. The proposal work is aimed at obtaining a composite material with good surface finish and with less
casting effects. By testing, we obtained the increase in surface roughness values of 3.83 µm at 4.5% of graphite and found
porosity is increased up to 0.04%.
Introduction. Nowadays for the light weight applications, aluminium-matrix composites are
extensively used in all mechanical fields for pre-existing structure that have to be retrofitted to make
them seismic resistant, or to repair damage caused by seismic activity. Aaron Lam et al. [1] did the
experimental studies on aluminium alloy 2219 have been formed the creep-aged at 175ºC for 18 h.
Using the CAF material constants determined for this alloy, corresponding finite element models have
been developed and experimentally validated using the measured profiles. Suresh et al., [2]
investigate the Aluminium composites have been produced with copper-coated cenospheres of fly
ash as reinforcement. The results indicate that with increasing percentage of reinforcement, the tensile
strength, impact strength and wear resistance of composites increases up-to 10%. Dunia Abdul Saheb
[3] study the modest attempt has been made to develop aluminium based silicon carbide particulate
MMCs. An increasing of hardness and with increase in weight percentage of ceramic materials has
been observed. The best results (maximum hardness) have been obtained at 25 % weight fraction of
SiC and at 4% weight fraction of graphite. Rajasekaran, & Sampath [4] Aluminium alloy AA2219
was reinforced with TiB particles introduced in-situ by the salt- metal reaction technique and the
results proved that the addition of TiB particles results in increased mechanical properties, such as
0.2%YS, UTS and hardness. Chunlin He et al.,[5] Analysed the corrosion protection from sulphuric
acid anodized coatings on 2024 aluminium and SiC particle reinforced 2024 aluminium metal matrix
composite (SiCp/2024Al MMC) The results show that the anodized coating on 2024Al provides good
corrosion protection to 3.5 wt. % NaCl. Krupinski et al., [6] investigated AlSi7Cu3Mg aluminium
cast alloy was performed for samples cooled with different cooling rate settings. Results observed
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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12
that phase morphology changes increase in relation to the cooling rate for the Al-Si-Cu alloy. The
amount of the pores increases together with the cooling rate. Hashim et al., [7] Combining high
specific strength with good corrosion resistance, metal matrix composites (MMCs) are materials that
are attractive for a large range applications. Vijayaramnath et. al. [8] studied the effect of
reinforcements of aluminium by the addition of different metals. Suryanarayana et. al. [9] studied the
SiC reinforced particles with aluminium for aerospace applications. Rupa Dasgupta [10] investigate
the effect of dispersing SiC in 2014 base alloy adopting the liquid metallurgy route on different wear
modes like sliding, abrasion. P.B. Pawar et.al studied [11] investigate the composite prepared by stir
casting technique, conducted Mechanical tests such as hardness test, microstructure test find out the
properties. Manoj Singla et.al.[12] modest attempt has been made to develop aluminium based silicon
carbide particulate MMCs with an objective to develop a conventional low cost method of producing
MMCs. C. Saravanan et.al. [13] studied the combined effect of reinforcements on Aluminium Metal
Matrix composites with individual and multiple particulate reinforcements like Hybrid Metal matrix
composites are finding increased applications in aerospace. Michael oluwatosin et.al. Reviewed the
different combination of metals along with aluminium alloy and investigate the change in properties.
In the present work, we reinforced the graphite in different percentage that it was not done before in
the previous work and we obtained the good results in surface roughness and porosity.
Properties of aluminium values
Density (g/cc) 2.84
Hardness (BHN) 49.5
Ultimate tensile strength (Mpa) 455
Modulus of elasticity (Gpa) 73.1
Poisson’s ratio 0.33
Shear strength (Gpa) 285
Thermal conductivity (W/m-K) 120
Melting point (◦C) 643-750
Table 1. Properties of graphite.
Bulk Density (g/cm
3
)
1.3-1.95
Porosity (%)
0.7-53
Modulus of Elasticity (GPa)
8-15
Compressive strength (MPa)
20-200
Coefficient of Thermal Expansion (x10
-6
°C)
1.2-8.2
Thermal conductivity (W/m.K)
25-470
Specific heat capacity (J/kg.K)
710-830
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Experimental work.
Fabrication of the project
Fabrication of composite bar.
Specimen preparation.
Testing of the specimen
Fabrication of composite bar.
Stir casting. Stir casting is a liquid state method of composite materials fabrication, (is shown in fig.
1) in which a dispersed phase (ceramic particles, short fibres) is mixed with a molten matrix metal by
means of mechanical stirring. The liquid composite material is then cast by conventional casting
methods and may also be processed by conventional metal forming technologies.
Fig. 1. Mechanical stirring machine.
Aluminium Stir Casting Equipment. In a stir casting process, the reinforcing phases are
distributed into molten matrix by mechanical stirring. An interesting recent development in stir
casting is a two-step mixing process. In this process, the matrix material is heated to above its liquids
temperature so that the metal is totally melted.
Adding of Graphite with Melted Aluminium alloy. The melt is then cooled down to a temperature
between the liquids and solidus points and kept in a semi-solid state. At this stage, the preheated
particles are added and mixed. The slurry is again heated to a liquid state and mixed thoroughly. This
two-step mixing process has been used in the fabrication of aluminium.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
14
a) B)
Fig. 2. Cast Piece (a) of the Composite Bar (b)
Cast Piece of the Composite Bar. Among all the well-established metal matrix composite fabrication
methods, stir casting is the most economical. The distribution of the particles in the molten matrix
depends on the geometry of the mechanical stirrer in the melt, melting temperature, and the
characteristics of the particles added.
Parameters used in stir casting. There is various process parameters if they properly controlled can
lead to the improved characteristic in composite material.
· Stirring speed - 500rpm
· Stirring temperature - 1023K
· Stirring time - 10min
· Preheating time of WC - 30min
· Preheating temp of WC - 473K
Composition of the specimen prepared.
Total weight is 750grams required to fabricate the composite bar (100%).
1. Aluminium 738.75gm with 1.5% of WC- 11.25gm.
2. Aluminium 727.5gm with 3% of WC- 22.5gm.
3. Aluminium 716.25gm with 4.5% of WC-33.75gm.
Specimen preparation. Here the specimens are prepared as per the size requirement for the
mechanical testing to be carried out for these materials.
Hardness test. Hardness is defined as the ability of the material to resist plastic deformation, usually
by indentation. Hardness is a measure of how resistant solid matter is to various kinds of permanent
shape change when a compressive force is applied. Some materials, such as metal are harder than
others. Resistance of a material to deformation, indentation, or penetration by means such as abrasion,
drilling, impact, scratching, and/or wear, measured by hardness tests such as Brunel, Knoop,
Rockwell, or Vickers. Since there is no standard hardness scale, each test expresses its results in its
unique measure.
Brunel hardness test. Method of measuring the hardness of a material by pressing a chromium-steel
or tungsten-carbide ball (commonly one centimetre or 0.4 inch in diameter) against the smooth
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
15
material surface under standard test conditions. The hardness is expressed in Brunel Hardness
Number (BHN) computed by dividing the load in kilograms by the area of indentation made by the
ball measured in square millimetres. American Society for Testing and Materials standard BH test is
ASTM E-10. For measurement up to BHN 500, Brunel hardness is equal to 0.96 times the Vickers
hardness.
Fig. 3. Brunel hardness Equipment.
Table 2. Tests results.
% of
Graphite
Force
Applied
(N)
Intender
(dia) mm
Trial
I
mm
Trial
II
mm
Trial
III
mm
Average
(dia)
mm
Brunel Hardness
Number (BHN)
1.
250
5.0
2.8
2.8
2.8
2.8
37.14
3.
250
5.0
2.9
2.8
2.9
2.845
34.8
4.
250
5.0
3.1
2.9
2.9
2.965
32.65
Surface roughness test. Surface roughness often shortened to roughness, is a component of surface
texture. It is quantified by the deviations in the direction of the normal vector of a real surface from
its ideal form. If these deviations are large, the surface is rough; if they are small, the surface is
smooth. It is often necessary to know both amplitude and frequency to ensure that a surface is fit for
a purpose.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
16
Fig. 4. Surface roughness tester.
Table 3. Rockwell tests results.
Type
Insert
Used
Spindle
Speed
(rpm)
Feed
Rate
Depth of
Cut
(mm)
Al Alloy
(%)
Graphite
(%)
Trial I
Trial II
Trial III
Average
Surface
Roughness
(µm)
Triangular
Insert
750
0.06
4
98.5
1.5
1.45
1.1
1.2
1.25
Triangular
Insert
750
0.06
4
97.0
3.0
2.5
2.4
2.7
2.53
Triangular
750
0.06
4
95.5
4.5
3.8
3.9
3.8
3.83
Porosity. Porosity or void fraction is a measure of the void or empty spaces in the material, and is a
fraction of the volume of void over the total volume, between 0 and 1, or as a percentage between 0
and 100%. Strictly speaking, some tests measures the accessible void”, the total amount of void
space accessible from the surface.
Table 4. Porosity tests results.
Composition of
Graphite
Volume
Mass ( gm)
Density(kg/cm³)
Porosity
Before
After
Before
After
1.5
5.4
14.966
14.966
2.77
2.77
-
3.0
5.4
13.731
13.737
2.54217
2.54388
0.02
4.5
5.4
15.267
15.270
2.82722
2.8277
0.04
Summary
The following conclusions were drawn from the AA2219 metal matrix composite after
conducting the experiments and analysing the results:
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
17
Based on hardness test results, the sample A (Al 98.5% & graphite 1.5%) is having maximum
hardness of 37.14 BHN.
Based on the porosity test results, the sample A (Al 98.5% & graphite 1.5%) is having minimum
casting defect.
Based on the surface roughness results, the sample A (Al 98.5% & graphite 1.5%) is having
minimum surface roughness value of 1.25µm.
It is concluded, that the minimum amount of graphite percentages (1% to 2%) is preferable for
many applications such as clutches, piston, spoilers, flight controls etc.
References
[1] H. Abdoli, E. Salahi, H. Farnoush, K. Pourazrang, “Effect of processing parameters on the
corrosion behaviour of friction stir processed AA2219 aluminium alloy”, Solid state sciences, J.
Alloys Compd. 461, 2008, 166172.
[2] Dunia Abdul Saheb “Aluminum silicon carbide and aluminum graphite particulate composites”
vol. 6 (10) , 2011, 41-46.
[3] S.R. Koteswara Rao, G. Madhusudhan Reddy, K. Prasad Rao “Effect of repair welding on
electrochemical corrosion and stress corrosion cracking” 202, 2008, 283–289.
[4] Koteswara Rao, S.R. Ph.D. Thesis. 2005. Effects of welding processes, thermo mechanical
treatments and scandium additions on the mechanical properties of AA 2219 welds”. Indian Institute
of Technology Madras, Chennai, India,
[5] A. Mahamani Procedia Materials Science “Effect of In-Situ TiB2 Particle Addition on the
Mechanical Properties of AA 2219 Al Alloy”, Composite” 6, 2014, 950 960.
[6] N.R. Rajasekaran, V. Sampath, “Synthesis behaviour of Nano crystalline AlAl2O3composite
during low time mechanical milling process”. Vol. 10 (6), 2011 527-534.
[7] B.Vijayaramnath, C.Elanchezhian, R.M. Annamalai , “Aluminium metal matrix composites A
Review”, Rev. Adv. Material science. 38, 2014, 55-59.
[8] Surya narayanan, R.Praveen, S.Raghuraman , SiC reinforced Aluminium metal matrix
composites for Aerospace applications”, International Journal of Innovative research in science and
Technology”, vol 2 (11), 2013, 6336-6339.
[9] Rupa Dasgupta, Aluminium Alloy-Based Metal Matrix Composites: A Potential Material for
Wear Resistant Applications”, ISRN Metallurgy, Vol (12), 2015, 253-259.
[10] P.B. Pawar, purushottampawar, Abhay A. Utpat Development of Aluminium Based Silicon
Carbide Particulate Metal Matrix Composite for Spur Gear”, Procedia Materials Science ,Volume 6,
2014, 1150-1156.
[11] Manoj Singla, D. Deepak Dwivedi, Lakhvir Singh, Vikas Chawla “Development of Aluminium
Based Silicon Carbide Particulate Metal Matrix Composite”, Journal of Minerals & Materials
Characterization & Engineering, Vol. 8 (6), 2009, 455-467.
[12] C. Saravanan, Subramanian, V.Ananda Krishnan “Effect of Particulate Reinforced Aluminium
Metal Matrix Composite”, Review Mechanics and Mechanical Engineering Vol. 19 (1), 2015, 23
30.
[13] Michael oluwatosin, Kenneth kanayo alanine, Lesley heath chown “Aluminum metal matrix
Hybrid composites: a review of reinforcement philosophies; mechanical, corrosion and tribological
characteristics” vol 2 (11), 2015, 434-444.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
18
Process Optimization of Warm Laser Shock Peening without Coating for
Automotive Spring Steel
S. Prabhakaran
1
, S. Kalainathan
1,a
1 Centre for Crystal Growth, VIT University, Vellore, India
a spkaran.kmd@gmail.com, s.kalainathan@gmail.com
DOI 10.2412/mmse.91.76.916 provided by Seo4U.link
Keywords: warm laser shock peening (WLSP) without coating, residual stress, hardness, dynamic strain aging, dynamic
precipitations.
ABSTRACT. The current study proposes and optimizes the process parameters for warm laser shock peening without
ablation coating. Warm laser shock peening brings up the advantage of dynamic strain aging and dynamic precipitation
hardening of metallic materials. The low energy Nd: YAG laser at the fundamental wavelength of 1064 nm utilized for
the operation and the borosilicate (BK7) glass was used as a confinement medium. The experiment performed with
different laser pulse densities and the results revealed that the higher pulse densities lead to surface melting due direct
ablation taking place on the pre warmed specimen surface. Also, the process temperature optimization was carried out
and the result indicates that there was a hardness drop during the laser peening at 300
o
C, which is due to an excess amount
of precipitation leads to lose the strength of the metal. The microstructural analysis was performed using the field emission
scanning electron microscope (FE-SEM).
Introduction. The post-processing material designing technology in automotive and aerospace
industries is playing a vital role. Most of the fatigue cracks are initiating at the surface and it
propagates throughout the material leading to fatigue fracture. The surface modification technologies
like cold rolling, ball milling, surface attrition treatment, shot peening and laser shock peening (LSP)
are used to modify the surface mechanical properties of metallic materials. Among these, the shot
peening is a mechanical cold working process that can induce compressive residual stress through a
number of successive shots using spherical iron balls, water jet and oil jet. Here, the induced
compressive residual stress (RS) effectively retards the fatigue crack initiation and propagation [1],
[2], [3], [4].
The laser based materials processing techniques are emerging from a decade because of its all round
performance like reliability and consistency in the industries. LSP emerges as a novel cold working
surface modification technique through inducing deep and high compressive residual stress [1], [5],
[6]. The basic phenomena behind this LSP process are the laser matter interaction producing high
pressure ionized gas plasma on the metal surface induces strong compressive shock waves into the
material and this compressive stress production is purely a cold working process [5] ,[6]. Normally
water or glass is utilized as the transparent confinement medium and black paint or PVC tape used as
surface protective ablation medium for LSP process. Ganesh et.al [2] ,[3] introduced the investigation
of LSP on spring steel for automotive applications and LSP has effectively repaired the fatigue life
of partly fatigued SAE 9260 spring steel using poly vinyl chloride (PVC) tape as an ablative medium.
The LSP producing grain refinement induced plastic deformation is liable to the fatigue life
enhancement of metallic materials [1-3]. The ambient condition LSP treatment induced internal RS
relaxation affects the mechanical properties of metal materials under exposure thermal conditions [1],
[4]. The thermal engineering based warm laser shock peening (WLSP) got advantages such as
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
19
dynamic strain aging (DSA), and dynamic precipitations (DP) hardening of low-alloy steel
contributing an extensive improvement in fatigue life cycle [1], [7]. LSPwC method of producing
high compressive RS works effectively with low energy lasers, also it is economical for commercial
applications [1], [4], [5].
Experiments and methods. A high content of Si & Mn medium carbon low alloy steel SAE 9254
hardened (900
0
C) and tempered (500
0
C) used for the laser surface modification process. The LSPwC
performed at room temperature (25
0
C) and pre-warmed (250 ± 15
0
C ) specimens with a low energy
Nd: YAG laser (300 mJ) of pulse duration 10 ns by the fundamental frequency of 1064 nm without
any confinement medium for both the processes. An experiment performed with the optimized
parameters such as laser spot diameter of 0.8 mm. The laser power density used for the current
experimental process is ~ 6 GW cm
-2
. The borosilicate glass (BK7) is used as the confinement layer
for the experiments. In order to avoid fast cooling of pre-heated specimen the electrical dryers are
used for continues heating of targeting specimen and its surroundings during WLSP experiment.
Subsequently, the WLSP treated specimen slowly cooled from the processing temperature to avoid
RS relaxation by fast cooling [1,7,8]. The mirror polished surface would not act as an opaque medium
but since it is polished transparent surface. An aluminium foil is not an opaque layer and there is an
experimental coating difficulty because of the high-temperature processing. In the case of high energy
laser, an increased thickness of the protective surface needs to be maintained [1].
Results and discussion
Laser pulse density optimization based on the residual stress analysis
Table 1. Residual stress results for the different pulse densities of LSPwC.
Specimen with pulse density
Surface residual stress (MPa)
Residual stress at 50 μm
depth (MPa)
Unpeened
124
196
LSPwC (800 pulses/cm
2
)
-302
-305
LSPwC (1600 pulses/cm
2
)
-330
-397
LSPwC (2500 pulses/cm
2
)
-349
-489
LSPwC (3900 pulses/cm
2
)
-294
-463
The residual stress was measured using to X-ray diffraction sin
2
Ψ method. The X-ray irradiations at
the diffractive angle (81.92
0
) are measured by X’pert Pro system (PANalytical, Netherlands) using
Cu
Kα
-radiation. The electrolyte polishing successive layer removal technique adopted for sub-surface
analysis of residual stress. The surface and sub-surface (at 50 μm) residual stress values were
considered for the optimization of laser pulse density. The laser pulse density of 800 pulses/cm
2
was
induced the compressive residual stress of - 302 MPa and - 305 MPa on the surface and sub-surface
(at 50 μm) respectively. Likewise, the laser pulse density of 1600 pulses/cm
2
induced -330 MPa and
-397 MPa compressive stress on the surface and sub-surface (at 50 μm) respectively. The laser pulse
density of 2500 pulses/cm
2
induced -349 MPa and -489 MPa compressive stress on the surface and
sub-surface (at 50 μm) respectively and which is the maximum compressive residual stress. Because
the higher pulse density at 3900 pulses/cm
2
induced only -294 MPa and -463 MPa compressive
stresses on the surface and sub-surface (at 50 μm) respectively due thermal effect producing surface
damage [1], [4].
Process temperature optimization: Vickers microhardness evaluation
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
20
Fig. 1. Vickers microhardness profile of different temperature war laser shock peening.
The transverse cross-sectional specimens are used to measure Vickers microhardness with a constant
load of 200 g. The excess amount of precipitation will lead to lose the strength of any material.
Likewise, the process temperature optimization is an important task to control the precipitation level
with the study metal SAE 9254 spring steel. The process temperature optimization were carried out
from 100
0
C to 300
0
C at an interval of 50
0
C. The WLSP without coating at 100
0
C to 250
0
C is
showing the improved hardness drastically. In the case of 300
0
C WLSP, the hardness was decreased
due to excess amount precipitaions formed during this process lead lose the strength of the material.
The average microhardness of unpeened specimen is around 343 HV. The WLSP at 250
0
C improved
to 427 HV from 343 HV and it shows around 25% of improvement in hardness. Also, the graph
indicates that the hardening effect is more in the sub-surface than the surface for all the temperature
range of process due to direct laser ablation treatment[1,4,5,7,8-10].
Microstructure analysis
Fig. 2. SEM of unpeened and FE-SEM of warm laser shock peening without coating specimen surface
morphologies.
The SEM microstructure indicates unpeened specimen microstructure as shown in Fig. 2a. The FE-
SEM shows the precipitations and refined grains produced by WLSP process as shown in Fig. 2b.
The precipitations in the nano range are clearly seen in Fig. 2a. These carbide precipitations are
(a
)
(b
)
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
21
blocking or filling the grain boundaries and increases the dislocation density of the metallic materials.
In such a case excess amount of precipitation will affect the material strength. Due to dynamic strain
aging and dynamic precipitations the material will get hardened and the mechanical properties such
that fatigue life can be improved[1], [4], [9], [10].
Summary. The low energy Nd: YAG laser with the fundamental wavelength was utilized for the
conventional warm laser shock peening process successfully. The higher laser pulse densities
producing thermal effect affect the induction of compressive residual stress and its magnitude. The
laser pulse density of 2500 pulses/cm
2
is optimized for the SAE 9254 spring steelfor automotive
applicatons.The process temperature for the warm laser shock peening without coating is optimized
and the higher temperture (above 250
0
C) is lead lost the hardness of the metal. So, this indicates that
the excess amount of precipitation may affect the machanical properties of the metallic materials.
References
[1] S. Prabhakaran, S. Kalainathan (2016), Warm laser shock peening without coating induced phase
transformations and pinning effect on fatigue life of low-alloy steel. Materials & Design, pp. 98-107,
DOI 10.1016/j.matdes.2016.06.026
[2] P. Ganesh, et al. (2012), Studies on laser peening of spring steel for automotive
applications. Optics and Lasers in Engineering 50 (5), pp. 678-686, DOI
10.1016/j.optlaseng.2011.11.013
[3] P. Ganesh, et al. Studies on fatigue life enhancement of pre-fatigued spring steel specimens using
laser shock peening, Materials & Design, 54, 2014, pp. 734-741, DOI 10.1016/j.matdes.2013.08.104
[4] S. Prabhakaran, S. Kalainathan. Compound technology of manufacturing and multiple laser
peening on microstructure and fatigue life of dual-phase spring steel. Materials Science and
Engineering: A 674, 2016, pp. 634-645, DOI 10.1016/j.msea.2016.08.031
[5] Kalainathan, S., S. Prabhakaran. Recent development and future perspectives of low energy laser
shock peening. Optics & Laser Technology, 81, 2016, pp.137-144, DOI
10.1016/j.optlastec.2016.02.007
[6] Ramkumar, K. Devendranath, et al. Influence of laser peening on the tensile strength and impact
toughness of dissimilar welds of Inconel 625 and UNS S32205. Materials Science and Engineering:
A 676, 2016, 88-99, DOI 10.1016/j.msea.2016.08.104
[7] Ye, Chang, et al. Fatigue performance improvement in AISI 4140 steel by dynamic strain aging
and dynamic precipitation during warm laser shock peening. Acta materialia 59 (3), 2011, pp. 1014-
1025, DOI 10.1016/j.actamat.2010.10.032
[8] Liao, Yiliang, Chang Ye, Gary J. Cheng. A review: Warm laser shock peening and related laser
processing technique. Optics & Laser Technology 78, 2016, pp.15-24, DOI
10.1016/j.optlastec.2015.09.014
[9] Podgornik, B., Leskovšek, V., Godec, M., b. Sencic. Microstructure refinement and its effect on
properties of spring steel. Mater Sci Eng A 599, 2011, pp. 8186.
[10] Scuracchio, B.G., de Lima, N.B., Schon, C.G,. Role of residual stresses induced by double
peening on fatigue durability of automotive leaf springs. Mater Des 47, 2013, pp. 672676, DOI
10.1016/j.matdes.2012.12.066
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
22
Studies on 1-Butyl 3-Methylimidazolium Hexafluorophosphate Incorporated
PVC-PBMA Polymer Electrolytes
R. Arunkumar
1
, Ravi Shanker Babu
1
, M. Usha Rani
1
1 Department of Physics, School of Advanced Sciences, VIT University, Vellore, Tamilnadu, India
DOI 10.2412/mmse.59.9.873 provided by Seo4U.link
Keywords: ionic liquids, LiPF
6
, solution casting techniques, impedance analysis, SEM analysis.
ABSTRACT. Polymer electrolytes consisting of polyvinyl chloride (PVC) and poly (butyl methacrylate) (PBMA) as
polymers, lithium hexafluorophosphate (LiPF
6
) as complex salt and 1-butyl 3-methylimidazolium hexafluorophosphate
(BmImPF
6
) as plasticizer were prepared by solution casting technique. The effect of ionic liquid (BmImPF
6
) on PVC-
PBMA blend polymer electrolytes are investigated by AC impedance, dielectric and SEM analysis to elucidate their
electrical, dielectric and surface morphological assessment. Ionic conductivity of the prepared polymer electrolytes is
found to be in the order of 10
-3
S cm
-1
. Polymer electrolyte with PVC-PBMA-LiPF
6
-BmImPF
6
(17-17-06-60) is found to
be a potential candidate in battery applications.
Introduction. Tremendous research on solid polymer electrolytes with salt/plasticizer/ceramics
replaces liquid electrolytes in lithium batteries because of limitations in liquid electrolytes, like
corrosion, leakage, flammability, degradation etc. Solid polymer electrolytes (SPE) fulfil those
drawbacks and further SPE are highly compatible with electrodes when compare to its counterparts
[1], [2], [3]. Solid polymer electrolytes based lithium batteries are used as power sources (electronic
devices) in laptops, digital cameras, mobile phones, hybrid electric vehicles (HEVs), plug-in hybrid
electric vehicles (PHEVs) and as batteries for electric vehicles (EVs) [4], [5]. The main drawback
with solid polymer electrolyte battery is its poor ionic conductivity at room temperature. To increase
the room temperature ionic conductivity, several methods like addition of plasticizer, blending of
polymers, crosslinking of polymer, incorporation of inorganic fillers and ionic liquids (ILS) are
reported. Among this, the present work focuses on ionic liquid based polymer electrolytes. Ionic
liquid doped polymer electrolytes have good ionic conductivity at low temperature because it can
dissociate the anion and cation easily at lower temperature due to the molten state of ILS is below
373K. Further ionic liquid doped polymer electrolytes have good thermal stability, non-flammability,
non-volatility, non-toxicity and wide electrochemical window [6]. The ionic liquid incorporated
polymer electrolyte batteries are operated at low temperature (313K) [7]. Ionic liquid have the
advantages of the previously mentioned properties when compared to those with organic solvents [8].
The present work reports the investigation on ILS doped polymer electrolytes. Extensively studied
on the variation in ionic conductivity, dielectric behaviour and morphology of polymer electrolytes
with BmImPF
6
carried out using ac impedance, dielectric and SEM analysis respectively.
Experimental. Polyvinyl chloride with average molecular weight 48000 g/mol, poly (butyl
methacrylate) with average molecular weight 337000 g/mol, lithium hexafluorophosphateand 1-butyl
3-methylimidazolium hexafluorophosphatewere procured from sigma Aldrich, USA.
PVC-PBMA polymer electrolytes with addition of BmImPF
6
at different ratios were prepared by
solution casting technique. The required amounts of substances were dried at 373K under vacuum at
10
-3
millibar for 10h. The dried polymers and salt were treated with pre-distilled tetrahydrofuran and
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
23
left undisturbed. The solution of PVC and PBMA were mixed together for 24h using a magnetic
stirrer followed by the addition of LiPF
6
and BmImPF
6
after 5h. The homogenous mixture was stirred
at elevated temperature until slurry was formed. The slurry transformed into Teflon coated glass
plate/petridishes and was left in vacuum atmosphere to evaporate the remaining solvent. The resultant
film was subjected to heat treatment toevaporatetheresidual solvent if any.
Conductivity and dielectric measurement of ILS incorporated PVC-PBMA polymer electrolytes were
carried out by using HIOKI 3532-50 LCR Hi TESTER meter in frequency range of 50Hz to 5MHz
with temperature difference 303 to 373K. Surface morphology of PVC-PBMApolymer electrolytes
were analysed by SEM analysis using Carl Zeiss EVO/185H,UK instrument and accelerating voltage
at 10kV.
Results and discussion
Conductivity studies
The ionic conductivity of the polymer electrolyte were calculated using the following relation:
=
(1)
where L thickness of the sample measured with using peacock meter;
A area of the film (A= π r
2
);
R
b
bulk resistance obtained from intercept on X-axis in Cole-Cole plot.
Temperature dependent ionic conductivity of ionic liquid doped PVC-PBMA polymer electrolytes
are depicted in Fig. 1a. Ionic conductivity of the polymer electrolytes increase with increase in
temperature. As the temperature increases polymer electrolyte can expand and produce more free
volume. In free volume, ionic transportation can occur between electrodes, which lead to
enhancement in ionic conductivity. Dependence of ionic conductivity on temperature for polymer
electrolytes doped with ionic liquid exhibited an increase of two orders of magnitude at 373K
(Table.1). Temperature dependent ionic conductivity of polymer electrolytes are found to obeys the
Vogel TammannFulcher (VTF) relation and it confirms the ionic conductivity occurs due to migration
of ions in a viscous matrix [9].
Fig. 1. Ionic conductivity of PVC-PBMA polymer electrolytes depends on (a) temperature and (b)
various concentrations of BmImPF
6
.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
24
Fig. 1 (b) shows the variation of conductivity with the variation of ionic liquid concentration. The
best room temperature ionic conductivity of the polymer electrolytes is found to be 1.284 x 10
-3
S cm
-
1
at 303K for film A5 which is four orders higher than the polymer electrolytes (0.017 x 10
-5
S cm
-1
at
303K) without ionic liquid. The increase in ionic conductivity with BmImPF
6
concentration is due to
(i) large number of ionic charge carriers provide by ILS since it has cautions (BmIm
+
) as well as
anions (PF
6
), further (ii) the low viscosity of BmImPF
6
also assist in increasing amorphicity or
reducing crystalinity of the polymer electrolytes which would ensure conformations in polymer chain
leading to segmental motion resulting in higher conductivity [10].
Table 1. Ionic conductivity of PVC-PBMA polymer electrolytes.
Sample
code
PVC:PBMA:LiPF
6
:
BmImPF
6
Ionic conductivity 10
-5
(S cm
-1
)
303K
318K
333K
353K
373K
A1
47:47:06:00
0.017
0.022
0.035
0.108
0.254
A2
37:37:06:20
0.052
0.093
0.162
0.461
1.320
A3
27:27:06:40
0.122
0.230
0.514
2.952
7.371
A4
17:17:06:60
3.912
6.631
8.256
55.06
153.1
A5
07:07:06:80
128.4
228.5
342.0
467.5
961.4
Dielectric studies
The real and imaginary part of dielectric constant (Ɛʹ&Ɛʺ) of PVC-PBMA polymer electrolytes are
evaluated using the following relation,
Ɛʹ =


(2)
Ɛʺ =

(3)
where C capacitance;
d thickness;
A area of the polymer electrolyte membrane;
conductivity;
ω angular frequency;
Ɛ
o
is permittivity of free space (8.854 x 10
-12
F/m).
The real (Ɛʹ) and imaginary part (Ɛʺ)of dielectric constant as function of frequency for 60 wt% of
ionic liquid incorporated PVC-PBMA polymer electrolytes at different temperature are depicated in
Fig. 2(a, b). The real and imaginary part of dielectric constant increase with increase in temperature,
which is due to increase in free ions and charge carrier density. The dielectric constants (Ɛʹ and Ɛʺ) of
PVC-PMA polymer electrolytes are high at low frequency and it decrease gradually with increase in
frequency and tends almost to zero at higher frequency denoting the presence of electrode polarization
effect.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
25
Fig. 2. Temperature dependent dielectric constant of PVC-PBMA polymer electrolytes (a) real part
and (b) imaginary part.
Dielectric modulus
The dielectric modulus was introduced by Macedo et al and is inversely proportional to the dielectric
constant. The real (Mʹ) and imaginary part (Mʺ) of dielectric modulus of PVC-PBMA polymer
electrolytes have been calculated by using the following relation:
Mʹ =
󰂢
󰂢
󰂣
(4)
Mʺ =
󰂣
󰂢
󰂣
(5)
where Ɛʹ, Ɛʺ– are real and imaginary part of dielectric constant respectively.
Frequency dependent real and imaginary dielectric modulus for 60 wt% of BmImPF
6
incorporated
PVC-PBMA polymer electrolytes are depicted in Fig.3a&b respectively. Both real and imaginary
part of dielectric modulus found to decreases at low frequencies, which implies negligible
contribution due to electrode polarization. The peak intensity for both real and imaginary modulus is
high for lower temperature at higher frequency region. The peak intensity of the dielectric modulus
decrease with increase in temperature may be due to the presence of plurality of relaxation
mechanism. The presence of long tail at low frequency is due to large capacitance associated with the
electrodes.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
26
Fig. 3. Temperature dependent dielectric modulus of PVC-PBMA polymer electrolytes (a) real part
and (b) imaginary part.
SEM analysis
Fig. 4. SEM image for 60 wt % BmImPF
6
incorporated PVC-PBMA polymer electrolytes at
different magnification (a) 3000x and (b) 7000x.
The surface morphology of the PVC-PBMA polymer electrolytes doped with 60 wt%BmImPF
6
at
different magnifications (3000&7000x) is shown in Fig. 4 (a, b).The presences of smooth and
ununiformed sized pores and further its helps in enhancing the ionic conductivity of the polymer
electrolytes.
Summary. PVC-PBMA blend polymer electrolytes with BmImPF
6
at different concentration were
prepared by solution casting technique. The temperature dependent ionic conductivity of PVC-PBMA
polymer electrolytes obeys Vogel Tammann Fulcher relation. The detailed frequency dependent
dielectric behaviour (Ɛʹ, Ɛʺ, Mʹ and Mʺ) of PVC-PBMA polymer electrolytes are discussed and
reported. These supporting the defence from conductivity studies which proves the high ionic
conductivity of PVC-PBMA polymer electrolyte with 60 wt% of BmImPF
6
exhibiting good stability
suitable for battery applications.
References
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
27
[1] Ramesh, S., Lu, S. C. (2008). Effect of nanosized silica in poly (methyl methacrylate)lithium bis
(trifluoromethanesulfonyl) imide based polymer electrolytes. Journal of Power Sources, 185 (2),
1439-1443.
[2] Armand, M., Tarascon, J. M. (2008). Building better batteries. Nature, 451(7179), 652-657
[3] Tang, C., Hackenberg, K., Fu, Q., Ajayan, P. M., Ardebili, H. (2012). High ion conducting
polymer nanocomposite electrolytes using hybrid nanofillers. Nano letters, 12(3), 1152-1156.
[4] Bernhard, R., Latini, A., Panero, S., Scrosati, B., Hassoun, J. (2013).Poly (ethylenglycol)
dimethyletherlithium bis (trifluoromethanesulfonyl) imide, PEG500DMELiTFSI, as high viscosity
electrolyte for lithium ion batteries. Journal of Power Sources, 226, 329-333.
[5] Barth, W. V., Hueso, A. P., Zhou, L., Lyons, L. J., West, R. (2014). Ionic conductivity studies of
LiBOB-doped silyl solvent blend electrolytes for lithium-ion battery applications. Journal of Power
Sources, 272, 190-195.
[6] Chaurasia, S. K., Singh, R. K., Chandra, S. (2013). Thermal stability, complexing behavior, and
ionic transport of polymeric gel membranes based on polymer PVdF-HFP and ionic liquid,
[BMIM][BF
4
]. The Journal of Physical Chemistry B, 117(3), 897-906.
[7] Shin, J. H., Henderson, W. A., Scaccia, S., Prosini, P. P., Passerini, S. (2006). Solid-state
Li/LiFePO
4
polymer electrolyte batteries incorporating an ionic liquid cycled at 40 C. Journal of
Power Sources, 156(2), 560-566.
[8] Choi, J. A., Kang, Y., Kim, D. W. (2013). Lithium polymer cell assembled by in situ chemical
cross-linking of ionic liquid electrolyte with phosphazene-based cross-linking agent. Electrochimica
Acta, 89, 359-364.
[9] Capiglia, C., Saito, Y., Yamamoto, H., Kageyama, H., Mustarelli, P. (2000). Transport properties
and microstructure of gel polymer electrolytes. Electrochimica Acta, 45(8), 1341-1345.
[10] Singh, P. K., Kim, K. W., Rhee, H. W. (2009). Development and characterization of ionic liquid
doped solid polymer electrolyte membranes for better efficiency. Synthetic Metals, 159(15), 1538-
1541.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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28
Conductivity Enhancement Studies on Poly (Acrylonitrile)-Poly (Vinylidene
Fluoride) Composite Polymer Electrolytes
M. Usha Rani
1
, Ravi Shanker Babu
1
, S. Rajendran
2
, R. Arunkumar
1
1 Department of Physics, School of Advanced Sciences, VIT University, Vellore
2 Department of Physics, Alagappa University, Karaikudi, India
DOI 10.2412/mmse.8.72.942 provided by Seo4U.link
Keywords: polymer electrolyte, composite, inert filler, plasticizer, impedance studies.
ABSTRACT. Composite electrolyte films consisting of poly (acrylonitrile), poly (vinylidene Fluoride), ethylene
carbonate, propylene carbonate, lithium tetra fluoroborate (LiBF
4
) and also titanium dioxide (TiO
2
) particles have been
prepared by solution casting technique. The effect of inorganic filler on the conductivity of the blended polymer
electrolyte has been studied. A conductivity of 3.1 x 10
-5
S cm
-1
is achieved at room temperature for the composition
PAN-PVdFLiBF
4
-EC-PC (21-10-8-33.3-27.7), whereas it improves two orders of magnitude (i.e. 5.624 ×10
3
S cm
1
)
upon dispersing fine particles of TiO
2
as inert filler into the matrix. The role of ceramic phase is to increase the ionic
conductivity and to reduce the melting temperature which is ascertained from conductivity and thermo
gravimetric/differential thermal analysis respectively.
Introduction. Decades ago, Wright and co-workers [1] pioneered the research on solid polymer
electrolytes and later Armand et al. [2] realized the potential applications of these materials in
batteries with high specific energy and other ionic devices. Even though, polymer electrolytes are
advantageous in terms of shape, geometry, mechanical strength and the potential for strong electrode
electrolyte contact, they have some disadvantages like, poor interfacial properties, low ionic
conductivity at ambient temperature [3]. Generally polymer electrolytes show practical ionic
conductivity only at higher temperatures, and their melting points, and at such high temperatures,
they exist in a ‘quasi-liquid’ state and become very flexible, and therefore show very poor
dimensional stability. A dimensionally polymer electrolyte film easily cause a short circuit between
a cathode and an anode when it is applied to all solid-state lithium battery. Increasing ionic
conductivity by increasing the salt concentration is ruled out because, higher salt content may favour
reduction in crystalline fraction of polymer but causes high ion-pairing interaction, which lead to salt
aggregation [4].
Hitherto several studies have been made primarily on the enhancement of ionic conductivity at
ambient temperature via various approaches such as blends, copolymers, comb-shaped polymers,
cross-linked networks, addition of plasticizers and incorporation of ceramic fillers onto the polymer
matrix [5]. Studies have revealed that plasticized polymer electrolytes lose their mechanical strength
upon addition of plasticizer and lead poor interfacial properties. The mechanical properties of the
polymer electrolytes can be increased either by chemical or physical curing which incurs high
processing cost. Recently, phase-inversion technique has drawn the attention of many researchers,
despite its advantages it suffers from poor rate capability [6]. Very recently, studies reveal that the
composite polymer electrolytes could offer lithium batteries with reliability and improved safety [6].
Many reports are available on the effect of ceramic oxides on polymer electrolytes such as, physical
and electrochemical properties, increase in cation transference number and improvement of
interfacial stability between the composite polymer electrolyte and lithium metal. In this work, novel
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
29
composite polymer electrolyte composed of PAN-PVdF-EC-PC-LiBF
4
-TiO
2
as promising electrolyte
for all solid-state lithium-ion batteries was prepared, and optimization for high ionic conductivity was
carried out by investigating the amount of ceramic filler incorporated.
Experimental. Poly (acrylonitrile) (PAN) (average molecular weight: 94000) and poly (vinylidene
fluoride) (PVdF) (average molecular weight: 534000) bought from Aldrich, USA were dried at 353K
under vacuum for 10 h; lithium tetra fluoroborate (LiBF
4
) (Aldrich) was dried at 343K under vacuum
for 24h. Plasticizer ethylene carbonate (EC) propylene carbonate (PC) (Aldrich) was used without
further purification. Titanium dioxide (TiO
2
) procured from Aldrich, USA of particle size <5 µm was
used after annealing at 373K for 10 h. All the electrolytes were prepared by solution casting technique.
Appropriate quantities of PAN, PVdF, LiBF
4
(Table 1) were dissolved by adding in sequence to pre-
distilled DMF (dimethylformamide. E. Merck, Germany). After incorporating the required amount
of plasticizer EC and PC, inorganic filler TiO
2
was suspended in the solution, stirred for about 48
hours at room temperature, and then at 333K for 4 h before the electrolytes were cast on finely
polished Teflon supports or Teflon covered glass plates. The films were dried in vacuum oven at
333K at a pressure of 10
3
Torr for 24 h. The thus obtained film was visually examined for its dryness
and free-standing nature. The obtained films were characterized by XRD, FTIR, conductivity,
TG/DTA and SEM analysis.
Results and discussion
Structural Analysis. The X-ray diffraction method has been used only in a limited perspective to
identify or confirm the amorphicity, complexation of the polymer electrolyte films. The X-ray
diffraction pattern of pure PAN, PVdF, LiBF
4
, TiO
2
and complexes are shown in Fig 1.(I)
respectively. Fig 1 [I. (b), (c) and (d)] reveals the crystalline nature of PVdF (with sharp peaks at 14º,
19º & 22 º), LiBF
4
and TiO
2
respectively. From the diffraction patterns it is obvious that there is a
decrease in relative intensity and broadening of the peak in the complexes. It may be due to the
addition of salt and blending of amorphous PAN, which induces a change in the crystallographic
organization in the crystalline PVdF. This result can be interpreted by considering the Hodge et al.
[7] criterion, which establishes a correlation between the height of the peak and the degree of
crystallinity. The effect of adding TiO
2
to the polymer complex is to improve ionic conductivity and
thermal stability. The sharp peaks in the spectrum of polymer complex [Fig.1. I. (g), (h) and (i)] reveal
the presence of undissolved TiO
2
in the polymer matrix, Fig 1. I. (e & f) show the effect of Tio
2
upon
PVdF which shows the reduction of crystallinity of PVdF. The diffraction peaks are found with lower
intensity till 10 wt% and found to increase on further addition indicating the increase in crystallinity
of the polymer electrolyte which may be responsible for the lowering of ionic conductivity. The
maximum ionic conductivity is found for PAN-PVdF-EC-PC-TiO
2
(10 wt %) polymer electrolyte
system which may be due to the higher amorphicity of the polymer electrolyte.
FT-IR spectroscopy is used to establish interaction between the constituents used in the complex. In
the present case, FT-IR is used to establish the interaction between the polymers, salt and plasticizers.
Such interaction can induce changes in vibrational modes of the atoms or molecules in the material.
The FTIR spectra obtained for pure PAN, PVdF, LiBF
4
, EC, PC, TiO
2
and the complexes in the range
of 4000 to 400 cm
-1
is shown in Fig. 1 [II (a-k)] respectively. The vibrational bands at 2942, 2245,
1250, 1074 cm
-1
in pure PAN is assigned to C-H stretching, CN stretching, C-N stretching, C-C
stretching respectively. The characteristic frequency of PVdF occurring at 1277, 1185, 854 cm
- 1
are
assigned to C-F stretching, C-F
2
stretching and characteristic frequency of vinylidine compound
respectively. These characteristic frequencies of PAN and PVdF mentioned above are found to be
shifted to 2952, 2243, 1076 and 1174, 881cm
-1
for PAN and PVdF respectively. The characteristic
frequency corresponding to C-N and C-F stretching are found to be absent in the complex. Some of
the absorption peaks corresponding to the primary constituents of the polymer complexes were found
to be shifted in the polymer complex. The absorption bands at (1455, 781, 640 cm
-1
) of PAN, (2996,
1554, 1165 cm
-1
) of EC, (2933, 1484 cm
-1
) of PC and 1320 cm
-1
of LiBF
4
are shifted to (1452, 777,
645 cm
-1
), (2291, 1556, 1170 cm
-1
), (2937, 1483 cm
-1
) and 1313 cm
-1
respectively. Apart from the
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
30
shift in peaks, there are some new peaks obtained at (2980, 2519, 1969, 1570, 974, 717 and 482 cm
- 1
)
in the complexes. The above analysis establishes the confirmation of complex formation.
Fig. 1. (I). XRD patterns of (a) PAN, (b) PVdF, (c) LiBF
4
, (d) TiO
2
and complexes PAN(21)-
PVdF(10)-LiBF
4
(8)-EC(33.3)-PC(27.7)-TiO
2
(X), (e) 0, (f) 5, (g) 10, (h) 15, (i) 20. (II). FTIR Spectra
of (a) PAN (b) PVdF, (c) LiBF
4
, (d) EC, (e) PC, (f) TiO
2
and complexes PAN(21)-PVdF (10)-
LiBF
4
(8)-EC(33.3)-PC(27.7)-TiO
2
(X), (g) 0, (h) 5, (i) 10, (j) 15, (k) 20.
Conductivity measurements. Inorganic filler (TiO
2
) dependent ionic conductivity of PAN-PVdF
composite polymer electrolytes are depicted in Fig.2. Evident from the isotherm (Fig. 2a), that, as the
concentration of ceramic increases, the conductivity is found to increase up to a certain concentration
(10 wt %) and then decrease Table 1. This increase in conductivity due to ceramic addition can be
attributed to (a) the ceramic particles acting as nucleation centres for the formation of minute
crystallites. (b) The ceramic particles aiding in the formation of amorphous phase in the polymer
electrolyte. (c) The formation of a new kinetic path via polymer ceramic boundaries (i.e. mobility of
ions through ceramic rich phase which entraps the residual solvents ensuing ion mobility). The
conductivity is not a linear function of filler concentration, at low concentration levels of TiO
2
, the
dilution effect which tends to depress the conductivity is efficiently contrasted by the specific
interactions of ceramic surface, which promote fast transport thus the net result is a progressive
enhancement of the conductivity. At higher filler content the dilution effect predominates and the
conductivity decays.
Temperature dependence of ionic conductivity is found to increase with increase in temperature (Fig.
2b) is due to polymer segmental motion. At higher temperature, the segmental motion either permits
the ions to hop from one site to another or provides necessary voids for ions to move in the polymer
matrix. As the temperature increases, polymer chains acquire faster internal modes in which the bond
rotations produce faster segmental motion. This in turn, favours the hoping inter and intra-chain ion
movements and the conductivity of the polymer electrolyte increases accordingly. The temperature
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
31
dependence of electrical conductivity (log vs. 1/T) indicates that the ionic conductivity obeys VTF
relation, which describes the transport properties in a viscous matrix. However, at lower temperature,
the presence of Li salt lead to salt-polymer or cation-dipole interaction, which increase the cohesive
energy of polymer networks. As the free volume decreases, polymer segmental motion and ionic
mobility are hindered, hence ionic conductivity decreases. It is found that PAN-PVdF-LiBF
4
-EC-PC
complex with 10 wt. % of TiO
2
has got the maximum room temperature conductivity of 5.624 X 10
-
3
S/cm which is higher compared to the system bereft of ceramic oxide.
Fig. 2. (a). Conductivity of PAN-PVdF-LiBF
4
-EC-PC System as a function of TiO
2
concentration,
(b). Arrhenius plot of log σ Vs reciprocal temperature of PAN( 21)-PVdF(10)-LiBF
4
(8)- PC(27.7)-
EC(33.3)- TiO
2
(X wt. %) 0 (1), 5 (2), 10 (3), 15 (4), 20 wt. %.
Table 1. Conductivity values of PAN(21)-PVdF(10)-LiBF
4
(8)-EC(33.3)-PC(27.7) with 5 different
composition of TiO
2
at different temperatures.
Films
Composition
of TiO
2
Conductivity values of PAN: PVdF : LiBF
4
: X TiO
2
in x 10
-3
S cm
-1
303 K
318 K
333 K
353 K
373 K
0
1
2
3
4
0
5
10
15
20
0.031
0.127
5.624
0.355
0.217
0.076
0.240
1.413
0.933
0.644
0.166
0.378
2.741
1.860
1.410
0.240
0.566
4.258
3.155
2.195
0.372
0.831
5.505
4.168
2.792
TG / DTA analysis
Thermal analysis of PAN-PVdF-EC-PC-LiBF
4
-TiO
2
(10 wt. %) system which shows maximum ionic
conductivity was carried out using PERKIN ELMER (Pyris Diamond) USA in the range 32 to 825°C
at a heating rate of 10°C/min. The TG/DTA spectrum of the sample mentioned above is shown in
Fig. 3.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
32
Fig. 3. TG/DTA curve for PAN(21)-PVdF(10)-LiBF
4
(8)-EC(33.3)-PC(27.7)-TiO
2
(10).
This shows an endothermic peak in DTA around 49-50°C associated with a weight loss of 9% which
may be due to the evaporation of moisture absorbed by the sample during loading. The polymer
electrolyte film is found to be stable till 279°C associated with a weight loss of 15% which could be
confirmed by the exothermic peak obtained around 253°C-321°C with a peak maximum at 290°C.
The weight loss of the polymer beyond 290°C is heavy which may be due to the decomposition of
the electrolyte constituents indicating the temperature range for efficient usage. Hence it is concluded
that the polymer electrolyte PAN(21)-PVdF(10) EC(33.3)-PC(27.7)-LiBF
4
(8)-TiO
2
(10) can be
effectively used in lithium polymer battery applications.
Scanning electron microscopic studies.
The microstructure of polymer blend films plays a vital role for effective use in practical applications.
Fig.4 exhibits the photographs of PAN (21) PVdF (10) LiBF
4
(8)- EC (33.3)-PC (27.7) - TiO
2
(10) at two different magnification i.e. 200 and 1000. Under these magnifications, it is seen that the
ceramic particles are so closely packed which would offer low unstable interfacial resistance by
reducing the growth of lithium passivation. Moreover the presence of ceramic fillers could
accommodate more amount of plasticizer and polymer matrix in between them (evident from Fig. 4a
and b respectively), which would help in withstanding the stress produced during fabrication and
functioning of this electrolyte in battery applications.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
33
Fig. 4. SEM photographs of PAN(21)-PVdF(10)-LiBF
4
(8)-EC(33.3)-PC(27.7)-TiO
2
(10) at (a 200
(b) 1000 magnifications.
Summary. Five different polymer electrolyte systems consisting of PANPVdFLiBF
4
EC- PC-
TiO
2
[TiO
2
=0, 5, 10, 15, 20 wt. %] have been studied. Of the five films, the film 2 is found to be the
best on the basis of conductivity and mechanical stability. The conductivity of the polymer electrolyte
PAN (21)-PVdF (10) EC (33.3)-PC (27.7)-LiBF
4
(8)-TiO
2
(10) is found to be maximum (5.624 X
10
-3
S/cm). The thermal stability of the film is estimated as 280°C. Hence, the properties (based on
the studies reported) of PAN (21)-PVdF (10) EC (33.3)-PC (27.7)-LiBF
4
(8)-TiO
2
(10) polymer
electrolyte look very promising for Li battery applications and could be used effectively.
References
[1] Fenton, D. E., Parker, J. M., Wright, P. V. (1973). Complexes of alkali metal ions with poly
(ethylene oxide). Polymer, Vol. 14(11), 589.
[2] Armand, M. B., Chabagno, J. M., Duclot, N. J., &Vashishta, P. (1979). Mundy, Shenoy (Eds.),
Fast Ion Transport in Solids.
[3] Appetecchi, G. B., Scaccia, S., Passerini, S. (2000). Investigation on the Stability of the Lithium
Polymer Electrolyte Interface. Journal of the Electrochemical Society, Vol. 147(12), 4448-4452, DOI
10.1149/1.1394084
[4] Reddy, M. J., Chu, P. P. (2002). Ion pair formation and its effect in PEO: Mg solid polymer
electrolyte system. Journal of power sources, Vol. 109(2), 340-346.
[5] Marcinek, M., Syzdek, J., Marczewski, M., Piszcz, M., Niedzicki, L., Kalita, M., Kasprzyk, M.
(2015). Electrolytes for Li-ion transportReview. Solid State Ionics, Vol. 276, 107-126.M.
[6] Appetecchi, G. B., Croce, F., Persi, L., Ronci, F., Scrosati, B. (2000). Transport and interfacial
properties of composite polymer electrolytes. Electrochimica Acta, Vol. 45(8), 1481-1490.
[7] Hodge, R. M., Edward, G. H., & Simon, G. P. (1996). Water absorption and states of water in
semi crystalline poly (vinyl alcohol) films. Polymer, Vol. 37(8), 1371-1376.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
34
A Comparative Study on the Dielectric Properties of Lanthanum Copper
Titanium Dioxide (La
2/3
Cu
3
Ti
4
O
12
) Ceramic with Conventional and Microwave
Sintering Routes
Surya Mallick
1
, Pawan Kumar
2
, M. Malathi
1, a
1 Condensed Matter Research Laboratory, Department of Physics, School of Advance Sciences, VIT University,
Vellore, Tamilnadu, India
2 National Institute of Technology, Rourkela, Odisha, India
a mmalathi@vit.ac.in
DOI 10.2412/mmse.6.46.507 provided by Seo4U.link
Keywords: microwave, conventional, dielectric, ceramics.
ABSTRACT. Lanthanum Copper Titanium Dioxide (La
2/3
Cu
3
Ti
4
O
12
, LCTO) precursor powders were synthesized by a
cost effective solid-state reaction. The material is sintered at two different techniques one is conventional and other one
is microwave. The microstructure and impedance characteristics were found to be strongly dependent on the sintering
conditions. The sintering has been done at 1, 000
o
C for 4 thin conventional method and for 20, 40and 60 min in microwave
method to compare the effects of two different sintering processes. X-ray powder diffraction study (XRD) analysis,
dielectric constant, dielectric loss and Scanning Electron Microscopy (SEM) results are observed. Structural properties
and phase formation was confirmed through XRD, this confirms Perovskite cubic structure of LCTO ceramics. Density
of the samples determined using Archimedes principle with water as liquid medium. SEM micrographs are taken and
results are being compared. Dielectric constant was investigated for different frequency values (1 kHz, 10 kHz, 100 kHz,
1 MHz) with temperature and the effective dielectric constant and loss as a function of frequency has been studied at
room temperature. Dielectric constant of microwave-sintered sample was found to be higher compared to the conventional
sintered sample at room temperature.
Introduction. Giant dielectric materials have become increasingly important due to the strong
technological needs for the further reduction of dimensional size and the enhancement of performance
in capacitance-based components like capacitors. In recent years a series of Perovskyte- related
structure material, ACu
3
Ti
4
O
12
(A= Ca
1
, La
2/3
2
, Y
2/3
3
, Na
1/2
Bi
1/2
4
, Na
1/2
La
1/2
5
) has been extremely
investigated because of its giant dielectric constant accompanied by low dielectric loss at room
temperature.La
2/3
Cu
3
Ti
4
O
12
(LCTO)is a member of the ACu
3
Ti
4
O
12
family but so far there are limited
literatures reporting LCTO ceramics out of them most studies are focused on preparation,
microstructure and dielectric properties of LCTO ceramics[1-3].LCTO ceramics can be fabricated by
a conventional solid state reaction [4]. However, the solid-state reaction has some disadvantages such
as long processing time, low purity and inhomogeneous grain size, which results in poor dielectric
properties. In general, the improvement of the fabrication methods is an effective way to improve
electrical characteristics of the ceramics. There are many alternative methods have been used to
prepare electronic ceramics which includes Sol-gel method, hydrothermal synthesis, combustion
route, spark plasma sintering , hot pressing, out of which Sol-gel method have been attempted to
prepare LCTO ceramics[1, 4]. However, these methods are complex and expensive which makes it
difficult in industrial application. Microwave sintering for electronic ceramics is superior to
conventional sintering owing to its unique characteristics, such as rapid heating, enhanced
densification rate and improved microstructure. Microwave heating differs significantly from
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
35
conventional heating. In the microwave, sintering process the heat is generated internally within the
material instead of originating from external sources and hence there is an inverse heating profile.
The heating is very rapid as the material is heated by energy conversion rather than by energy transfer,
which occurs in conventional techniques. Microwave sintering ensures considerable time and energy
saving, and therefore considered as one of the most prospective sintering techniques in material
processing. The method has been widely applied in the fabrication of electronic ceramics [5].
In this work, the LCTO ceramics were fabricated by conventional and microwave sintering. The
influence of sintering methods, sintering time on the microstructure and dielectric properties of LCTO
ceramics investigated systematically. The origin of high dielectric constant of LCTO was studied by
impedance analysis. From the XRD peaks, it has been shown that LCTO has a perovskite cubic
structure. LCTO ceramics produced from microwave sintering method giving uniform and dense
grain morphology. Several reports have shown that many factors, such as electrodes, grain boundaries
or domain boundaries are responsible for the high dielectric constant and further improvements in
dielectric properties have been studied [6, 7]. We believe that our present studies would help in
providing more insight and rationalizing the dielectric behaviour of the ceramics at different sintering
routes.
Experimental Methods. Polycrystalline ceramic powders of LCTO were prepared via the
conventional solid-state reaction route using stoichiometric amounts of La
2
O
3,
CuO and TiO
2
. The
raw materials were measured using the high precision balance machine. These were thoroughly mixed
in an acetone medium using a ball mill. Then the mixture was thoroughly grinded for one hour. This
was followed by the calcination of the powder in alumina crucible at 1, 000
o
C for 4, 6, 8and 12h, at
a heating rate of 5
o
C per minute in conventional furnace. During the calcination process, ferroelectric
phase is obtained because of solid phase reaction between the constituents. Single Phase formation
was confirmed through XRD. The XRD patterns of the samples were taken at an angle2θ
20≤2θ≤70
o
with a scanning rate of 2
o
per minute. The polycrystalline powder was then cold pressed into the
pallets using PVA as a binder. LCTO pallets were sintered in two different methods one is
conventional sintering and other one is microwave sintering. In conventional sintering process, pallets
were fired at one, 000
o
C for 4h whereas in microwave sintering process pallets were fired at 1,
000
o
Cfor 20, 40 and 60 min, respectively. Pallet densities were measured using Archimedes principle
using water as the liquid medium. The microstructural features and grain size distribution in sintered
pallets were studied by SEM. The grain sizes were found using Average Grain Intercept Method
(AGI) [7]. The dielectric constant measurement was carried out as a function of temperature for
different frequency values (1 kHz, 10 kHz, 100kHz, 1MHz), along with that dielectric constant and
loss as a function of frequency were measured at room temperature using independence gain phase
analyzer. For these purpose surfaces of sintered pallets sputtered with silver. Ideally silver should
adhere strongly to the ceramics, it should be very thin, practically zero resistance and with a good
chemical and physical durability.
Results and Discussions. Fig. 1 shows the XRD patterns of LCTO powders calcined for different
times (4, 6, 8 and 12 h). The XRD patterns are virtually the same and show only single
phaseperovskite (ABX
3
) structure, without the evidence of the second phase. XRD patterns of LCTO
ceramics are in agreement with the respective joint committee on powder diffraction standards (cubic,
space group- Im3, space group number- 204, JCPDS file no. 75-2188). As the calcination time
increases, the substance begins to melt, these results secondary peaks to the XRD pattern. From the
pattern, it has cleared that cupper and calcium has diffused completely into the LCTO ceramic lattice
to form a solid.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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36
Fig. 1. XRD pattern of LCTO calcined at 1, 000°C in conventional way for (a) 4h, (b) 6 h, (c) 8 h
and (d) 12h, ♣ -Unidentified Phase.
Fig. 2. SEM images of sample Sintered for (a) 4h, (b) 20 min, (c) 40 min and (d) 60 min.
Fig. 2 (a-d) show the surface morphologies of LCTO ceramics sintered at 1, 000
o
C for 4h in
conventional furnace and for 20, 40and 60minin microwave furnace. We termed conventionally
sintered sample for 4 hours as C-4 and microwave sintered sample for 20, 40, and 60 min as M-20,
M-40, and M-60, respectively. It is clear from the micrographs that the grains have smooth faces
associated with cubic appearance.
From the table 1 it can be shown that the gran size of the conventionally sintered sample (C-4) is less
compared to microwave sintered samples (M-20, M-40 and M-60). Ceramics with larger grain size
have a small volume fraction taken up by Schottky barriers at the grain boundary, which will lead to
the decrease of the effective thickness of charge storage regions. This may corresponds to the thinner
barrier width and consequently leads to larger dielectric constant [8], [9]. As the microwave sintering
time extends LCTO ceramics become uniform, denser and grain size increases. The sample M-20,
M-40 and M-60exhibits relatively homogeneous grain sizes and low porosity. Density of M-40 found
to be 5.06 g /cm
3
, which is comparatively higher than C-4.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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37
Table 1. Calculated grain sizes are listed below.
Sample code
Grain size (µm)
M-60
2.4
M-40
2.2
M-20
1.4
C-4
1.3
*
M- Microwave, C- conventional
Based on practical application, ceramics with high dielectric constant and low dielectric loss must be
selected firstly. Fig. 3 (a), shows the variation of dielectric constant with temperature at different
frequency values (1 kHz, 10 kHz, 100 kHz, 1 MHz), for M-40. It can be seen that there is a phase
transition from ferroelectric to paraelectric at Curie temperature (T
c
) (250
o
C, 1 kHz), large value of
T
c
can be found at higher frequency range (10
6
Hz). The Dielectric constants values showing weak
temperature and frequency dependence up to T
c
, after that it increases sharply with increase in
temperature which is due to increase in polarization at higher temperature. It is found that there is
weak temperature dependence of dielectric constant at higher frequency range, (10
6
Hz). Fig. 3 (b),
shows the variation of dielectric constant and dielectric loss of M-40as a function of frequency at
room temperature. Same analysis has been done for M-60, M-20 and C-4, which are not being shown
here. The results indicate that dielectric constant of M-40 is around 1.097, which is comparatively
higher than C-4at room temperature. All the samples reasonably exhibited high dielectric constants
at low frequencies. Furthermore, the dielectric losses of the microwave sintered samples for 20, 40
and 60 min are lower than that of the conventional sintered sample for 4 h at room temperature. The
dielectric loss of M-40 found out to be 1.04 at room temperature.
Fig. 3. (a)Variation of dielectric constant
r
) at different frequency values as a function of
temperature, (b) Variation of dielectric constant (ε
r
) and dielectric loss (tan
δ) with frequency at
room temperature forM-40.
Summary. The LCTO ceramics have been successfully prepared by microwave and conventional
sintering route. The effect of sintering process on microstructure and dielectric properties of LCTO
ceramics has been investigated systematically. The sample calcined for 4, 6, 8 and 12 h in
conventional heating are found out to be single phase perovskite cubic structure. SEM analysis
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38
showed dense microstructure in the sample with grain size of 1-2μm. As the microwave sintering
time extends the grain size and density of LCTO ceramics increases and the sample gradually
becomes denser. The microwave sintered pallets exhibited more homogeneous microstructure, less
porosity as well as comparatively higher value of dielectric constant (M-40, 1, 097) and lower value
of dielectric loss (M-40, 1.04) compared to conventional sintered sample (C-4) at room temperature.
M-40 showed much higher value of dielectric constant (40 x10
4
, at 10
3
Hz), which displays weak
temperature and frequency dependence over a certain temperature range. The Curie temperature (T
c
)
found out to be225
o
C at 1 kHz, the value increases at higher frequency range.
References
[1] Z. Liu, Z. Yang, X. Chao, Structure dielectric property and impedance spectroscopy of
La2/3Cu3Ti4O12 ceramics by solgel method, Journal of Materials Science: Materials in Electronics,
2016, 8980-8990. DOI 10.1007/s10854-016-4929-z
[2] B.S. Prakash, K.B.R. Varma, Effect of sintering conditions on the microstructural, dielectric,
ferroelectric and varistor properties of CaCu3Ti4O12and La2/3Cu3Ti4O12 ceramics belonging to
the high and low dielectric constant members of ACu3M4O12 (A=alkali, alkaline-earth metal, rare-
earth metal or vacancy, M=transition metal) family of oxides, Physica B: Condensed Matter, 2008,
22462254. DOI 10.1016/j.physb.2007.12.004
[3] B.S. Prakash, K.B.R. Varma, Effect of sintering conditions on the dielectric properties
ofCaCu3Ti4O12 and La2/3Cu3Ti4O12 ceramics: A comparative study, Physica B: Condensed
Matter, 2006, 312-319. DOI 10.1016/j.physb.2006.03.005
[4] Z. Liu, X. Chao, P. Liang, Z. Yang, L. Zhi, Differentiated Electric Behaviors
of La2/3Cu3Ti4O12Ceramics Prepared by Different Methods, Journal of the American Ceramic
Society, 2014, 2154-2163. DOI: 10.1111/jace.12940
[5] W. Cai, C. Fu, G. Chen, X. Deng, K. Liu, R. Gao, Microstructure, dielectric and ferroelectric
properties of barium zirconate titanate ceramics prepared by microwave sintering, Journal of
Materials Science: Materials in Electronics, 2014, 4841-4850. DOI 10.1007/s10854-014-2242-2
[6] L.Singh, U.S. Rai, K.D. Mandal, N.B. Singh, Progress in the growth of CaCu3Ti4O12 and related
functional dielectric perovskites, Progress in Crystal Growth and Characterization of Materials, 2014,
15-62. DOI 10.1016/j.pcrysgrow.2014.04.001
[7] Y. Pu, W. Chen, S. Chen, H.T. Langhammer, Microstructure and dielectric properties of
dysprosium-doped barium titanate ceramics, Ceramica, 2005, 214-218. DOI 10.1590/S0366-
69132005000300007
[8] B.S. Prakash, K.B.R. Varma, Influence of sintering conditions and doping on the dielectric
relaxation originating from the surface layer effects in CaCu3Ti4O12 ceramics, Journal of Physics
and Chemistry of Solids, 2007, 490-502. DOI 10.1016/j.jpcs.2007.01.006
[9] J. liu, R.W. Smith, W.N. Mei, Synthesis of the Giant Dielectric Constant Material CaCu3Ti4O12
by Wet- Chemistry Methods, Chemistry of Materials, 2007, 6020-6024. DOI 10.1021/cm0716553
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
39
Theoretical Investigation on the Structural, Elastic and Mechanical Properties
of Rh3HxNb1-x(x=0.125, 0.875)
M. Manjula
1
,
M. Sundareswari
1
1 Department of Physics, Sathyabama University, Chennai, India
DOI 10.2412/mmse.86.89.465 provided by Seo4U.link
Keywords: first-principles theory, density functional theory, electronic properties, mechanical properties, ductility.
ABSTRACT. Electronic, elastic and mechanical properties of Rh
3
H
x
Nb
1-x
(x=0.125, 0.87) are investigated from density
functional theory using FP-LAPW method within generalized gradient approximations. The lattice parameters and ground
state properties are calculated by using optimization method. Shear modulus, Young’s modulus, Poisson’s ratio, G/B ratio
and anisotropy factor are calculated using elastic constants C
11
, C
12
and C
44
. The calculated results are consistent with
available theoretical and experimental data. Systematic addition of Hf with Rh
3
Nb shows that the Rh
3
Hf
0.125
Nb
0.875
and
Rh
3
Hf
0.875
Nb
0.125
are ductile. Charge density plots assess the results.
Introduction. L1
2
intermetallic compounds such as rhodium and iridium based compounds are of
great interest in industrial applications [1], [2]. The mechanical and thermal findings on rhodium base
alloys are more convenient for high-temperature structural applications than iridium base alloys.
Rhodium is most frequently used as an alloying agent in other materials such as platinum and
palladium. These alloys are used to make electrodes for aircraft spark plugs, detectors in nuclear
reactors, laboratory crucibles and furnace coils. It has higher thermal conductivity, high temperature
strength, good oxidation resistances and lower thermal expansion coefficient which are beneficial
properties for high temperature applications [3], [4], [5], [6], [7], [8], [9]. The L1
2
crystal structure
offers the possibility of enhanced ductility and workability of these materials. This motivates us to
focus our research on rhodium base alloys. Especially, we focus our attention to design new materials
with enhanced ductility from existing one. Alloying is one of the effective ways to attain our aim. To
our best knowledge no systematic study on Rh
3
Hf
x
Nb
1-x
ternary alloy system. We have already
reported Rh
3
Hf
x
Nb
1-x
(x= 0.25.0.75) combinations in our previous work [10]. In the present study, a
first-principles calculation based on the density-functional theory was carried to investigate the
electronic structure and mechanical properties of Rh
3
Hf
x
Nb
1-x
(x= 0.125.0.875) combinations. The
ductile/brittle nature of these compounds is analysed.
A number of theoretical and experimental structural have been performed for structural, electronic,
elastic and mechanical properties of Rh
3
Nb. Yamabe et al. investigated the microstructure evolution
and high temperature strength of Rh-based alloys [11]. Rajagopalan and Sundareswari reported
structural and electronic properties of this compound [12]. Chen et al. [13] investigate elastic and
mechanical properties of this compound. The mechanical properties of Rh
3
Nb are studied by Miura
et al. [14]. Some of the thermal properties were measured by Terada et al. [15]. Their strength
behaviour was discussed by Yamabe-Mitarai et al. [16]
Computational Methods. Our calculations are carried out by means of Full Potential Linearized
Augmented Plane wave (FP-LAPW) method implemented in the WIEN2k code [17]. The basis set is
obtained by dividing the unit cell into non-overlapping spheres surrounding each atom and creating
an interstitial region between the spheres. The exchange and correlation was treated within the
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
40
generalized gradient approximation by Perdew et al [18]. 10×10×10 k-point mesh is used in the
irreducible Brillion Zone. The plane wave expansion is taken as R
MT
× K
max
= 7.0 and l
max
=10. Charge
density Fourier expansion are extended up to G
max
=12. The total energies are converged below
0.0001eV and the charges are converged below 0.001mRy.
Result and Discussion. The Rh
3
Nb alloy has a Cu
3
Au-type structure with space group 221-Pm3m.
The Rh and Nb atoms are located at the site (0, 0.5, 0.5) and (0,0,0) respectively. The optimized lattice
parameters for Rh
3
Nb, Rh
3
Hf
0.125
Nb
0.875
and Rh
3
Hf
0.875
Nb
0.125
are presented in Table 1 and calculated
lattice constant for Rh
3
Nb agree very well with experimental and theoretical data [12], [13]. For
Rh
3
Nb, the percentage error between the calculated and the experimental lattice constant is 1.07. The
calculated elastic constants (C
11
, C
12
and C
44
), Shear modulus (G), Young’s modulus (E), Cauchy
pressure (C
12
-C
44
), G/B ratio, Poisson’s ratio (ν), and anisotropy factor (A) for Rh
3
Hf
x
Nb
1-x
(x =0,
0.125, 0.875) combinations are reported in Table1 and these values are used to predict ductile/brittle
nature of the compounds. From Table 1, one can note that the computed B, G, E and C
44
values for
Rh
3
Nb are quantitatively higher than the other two combinations.
For cubic system there are three independent elastic constants namely C
11
, C
12
and C
44
. The
mechanical stability conditions for cubic crystal are: C
11
-C
12
>0, C
11
>0, C
44
>0, C
11
+2C
12
>0. The
calculated elastic constants (Table 1) obey the mechanical stability criteria, suggesting that these
compounds are mechanically stable.
Table 1. The optimized lattice parameter, elastic constants and elastic properties of Rh
3
Hf
x
Nb
1-x
(x=0,
0.125, 0.875).
Parameters
Rh
3
Nb
Rh
3
Hf
0.125
Nb
0.87
5
Rh
3
Hf
0.875
Nb
0.12
5
Lattice Constant (a.u.)
Present study
Other study
a
a
exp
=7.2887
a
cal
=7.3668
a
exp
=7. 289
a
cal
=7.3625
a
oal
= 7.3677
a
cal
= 7.4405
C
11
C
12
C
44
Cauchy Pressure(C
12
-C
44
)
Bulk Modulus(B), GPa
Shear Modulus(G), GPa
Young’s Modulus(E), GPa
G/B
475.48
169.58
456.58
-287.00
271.55
294.81
649.42
1.08
374.72
186.33
211.16
-24.83
249.13
152.73
380.44
0.61
322.10
174.16
102.88
71.28
223.47
90.14
238.38
0.40
Poisson’s Ratio(ν)
B/C
44
H
V
A
0.10
0.594
77.87
2.27
0.25
1.179
25.91
1.62
0.32
2.172
10.68
1.179
Bulk modulus is a measure of average atomic bond strength of materials [19]. It is strongly correlated
with cohesive energy or binding energy of atoms in crystals. The large value of shear modulus
indicates that the more pronounced directional bonding between atoms [20], [21]. Young’s modulus
(E) indicates the stiffness of the material. Higher its value the material will be stiffer. From Table 1,
the values of B, G and E reveals that the addition of Hf in Rh
3
Nb can decrease the atomic bond
strength, directional bonding and stiffness of the material.
Ductile/brittle nature of the alloy is investigated to analyse the effect on brittleness of Rh
3
Nb on
addition of hafnium. The ductility of the compounds investigated based on Cauchy pressure (C
12
-
C
44
), G/B ratio and Poisson’s ratio (ν). According to Pettifor [22], if C
12
-C
44
is positive, the material
exhibits metallic characteristics and it is negative for non-metallic with directional bonding. Rh
3
Nb
and Rh
3
Hf
0.125
Nb
0.875
are brittle having negative Cauchy pressure (-287GPa & -24.83) and
Rh
3
Hf
0.875
Nb
0.125
is ductile having positive Cauchy pressure (71.28GPa). According to Pugh criterion
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
41
[23], if G/B < 0.57 the material exhibits ductile behaviour, otherwise, it exhibits brittle behaviour.
This ratio for Rh
3
Hf
0.875
Nb
0.125
(0.39) is less than 0.57 reveals that ductile nature. Poisson’s ratio (ν)
[24] explains about the characteristics of the bonding forces. If ν >0.26, the material is ductile;
otherwise brittle. The ν value for Rh
3
Hf
0.875
Nb
0.125
is 0.33 indicates that the ionic contributions to the
atomic bonding are dominant for these compounds.
Elastic anisotropy factor (A) is an indicator of the degree of anisotropy in the solid structures [25].
For a complete isotropic material A=1, when the value of A is smaller or greater than unity it is a
measure of the degree of elastic anisotropy. From Table 1, it can be seen that the Rh
3
Nb is and
anisotropy material due to A>1. With the addition of Hf to Rh
3
Nb, the degree of anisotropy decreases.
The calculated microhardness H
V
[21] for Rh
3
Hf
0.125
Nb
0.875
and Rh
3
Hf
0.875
Nb
0.125
is 25.91 GPa and
10.68 GPa respectively (Table 1). From the calculations, it is found that the hardness decreases when
hafnium is added to the parent Rh
3
Nb alloy. Along with bulk and shear modulus, the elastic constant
C
44
is also an important parameter indirectly governing the indentation hardness [26]. Hence,
Rh
3
Hf
0.875
Nb
0.125
identified as less hard material having low hardness and C
44
values than
Rh
3
Hf
0.125
Nb
0.875
.
The results are assessed by plotting charge density plots. Fig. 1 (a-c) shows that the charge density
plots of Rh
3
Nb, Rh
3
Hf
0.125
Nb
0.875
and Rh
3
Hf
0.875
Nb
0.125
alloy combinations respectively. In general,
the brittle materials have strong directional characteristic of bonding. From Fig. 1a, one can observe
that the charge density contours encloses Nb-Rh-Nb atoms and this can be attributed to the directional
covalent nature (brittle). Such directionality is decreased in Rh
3
Hf
0.125
Nb
0.875
and Rh
3
Hf
0.875
Nb
0.125
when Nb is replaced by Hf (Hf-Rh-Nb) shown in Fig. 1b & 1c. In Fig.1c, the electron density contours
enclosing Hf & Rh atoms and Hf & Nb atoms are not observed. This makes the directional bonding
very weak, it may be attributed to the ductile nature of Rh
3
Hf
0.875
Nb
0.125.
Thus, addition of Hf to
Rh
3
Nb reduces the directional bonding nature present in Rh
3
Nb, resulting in a transition from brittle
to ductile nature in Rh
3
Hf
0.875
Nb
0.125.
(a) (b) (c)
Fig. 1. Charge density plot of (a) Rh
3
Nb (b) Rh
3
Hf
0.125
Nb
0.875
and (c) Rh
3
Hf
0.875
Nb
0.125
.
Fig. 2 (a-c) represents the DOS curves of Rh
3
Nb, Rh
3
Hf
0.125
Nb
0.875
and Rh
3
Hf
0.875
Nb
0.125
alloy
combinations respectively. From DOS histograms, it is observed that the peaks in the total density of
states that lie below the Fermi level are mainly due to the Rh-d states and above the Fermi level are
Nb-d and Hf-d states. In Fig. 2a, one can notice a pseudo gap in Rh
3
Nb and in Fig. 2 (b-c), there is
no noticeable pseudo gap in Rh
3
Hf
0.125
Nb
0.875
and Rh
3
Hf
0.875
Nb
0.125
combinations. The pseudo gap
can directly reflect the strength of covalent bonding.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
42
(a) (b) (c)
Fig. 2. DOS histograms of (a) Rh
3
Nb (b) Rh
3
Hf
0.125
Nb
0.875
and (c) Rh
3
Hf
0.875
Nb
0.125
.
The Debye temperature is one of the important parameter closely related to many physical properties.
It is a measure of thermal conductivity of materials and it can be related to the strength of covalent
bonds [27]. Using the elastic constants, the Debye temperature (
D
), sound velocities for longitudinal
and shear waves (V
L
and V
S
) and Debye average velocity (V
m
)[28] are calculated and presented in
Table 2. From Table 2, it can be found that the Debye temperature value for Rh
3
Hf
0.125
Nb
0.875
(618
K) and Rh
3
Hf
0.875
Nb
0.125
(448 K) alloy combinations are decreased. Hence, the strength of covalent
bonds decreases in these materials.
Table 2. Calculated mass density ρ (gm/cm
3
), V
L
and V
S
(10
3
m/s), Debye average velocity Vm
(10
3
m/s), and Debye temperature
D
(K) for Rh
3
Hf
x
Nb
1-x
(x=0,0.125,0.875)alloys.
Parameters
Rh
3
Nb
Rh
3
Hf
0.125
Nb
0.875
Rh
3
Hf
0.875
Nb
0.125
ρ
V
L
V
S
Vm
D
45.02
3.8422
2.5589
2.7970
857
46.21
3.1302
1.8180
2.0174
618
51.84
2.5747
1.3186
1.4770
448
Summary. In this work, the structural, elastic and electronic properties of Rh
3
Hf
x
Nb
1-x
(x =0, 0.125,
0.875) combinations are investigated by means first principles calculations based on DFT with GGA
method. The calculated lattice parameters and bulk modulus are consistent with the literature values.
Young’s modulus, shear modulus, G/B ratio, Poisson’s ratio and anisotropy factor have been
calculated and discussed. Also in Rh
3
Nb, a transition from brittle nature to ductile nature is observed
when Hf is added. Rh
3
Hf
0.875
Nb
0.125
shows ductile nature having highest Cauchy pressure and
Poisson’ ratio and lowest shear modulus, Young’s modulus and G/B ratio. Charge density plots reveal
decrease in directional bonding nature in Rh
3
Nb when Hf is added. The sound velocities and Debye
temperatures of the alloys have been calculated.
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Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
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Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
44
Synthesis and Characterization of Monolithic ZnO-SiO2 Nanocomposite
Xerogels
D. Prasanna
1
, P. Elangovan
1,a
, R. Sheelarani
1
1 Dept. of Physics, Pachaiyappa’s College, Chennai, Tamil Nadu, India
a drelangovanphysics@gmail.com
DOI 10.2412/mmse.57.4.239 provided by Seo4U.link
Keywords: nano composites xerogel, sol gel method.
ABSTRACT. Synthesis and characterization of ZnO doped SiO2 monolithic nano composite xerogels were prepared by
using sol-gel method. In this method prepared samples were observed, that an ageing period of two days is optimum and
a very slow controlled evaporation rate is followed for few days. The prepared ZnO-SiO2 monolithic nano composite
xerogels for various concentrations are characterized by X-ray diffraction, field-emission scanning electron microscope
and Fourier transform-infrared spectroscopy methods.
Introduction: ZnO nano particle embedded into SiO
2
composites have attracted extensive research
interests. It has been found that these materials have improved luminescence efficiency compared to bulk
ZnO material. Excellent non-linear optical properties, saturable absorption and optical bistability have
also been reported for these composites various techniques have been employed to prepare nano
ZnO-SiO
2
composites, including sol-gel impregnation and magnetron sputtering, etc. Wide varieties
of glass, glass-ceramic monolithics, nanostructural powders etc., are synthesized through sol-gel
technique. In the present work ZnO embedded into SiO
2
nanocomposites are synthesized through the
sol-gel process. The steps needed for producing monolithic xerogels are carefully followed.
Experimental.
Materials. Zinc acetate dihydrate (Zn (CH
3
COO)
2
2H
2
O), Triethanolamine (TEA) and Sodium
hydroxide (NaOH), Ethanol(C
2
H
6
O), Tetraethyl orthosilicate (TEOS) were purchased from s d fine-
chem. limited in Chennai.
Analyses. The starting solution is prepared by mixing TEOS, ethanol and water in the ratio of
10:10:14 respectively. The starting solution is stirred at 40C for few minutes. One drop of
concentrated HCl is diluted in 3 ml of deionized water, is added drop wise in the starting solution.
SAfter 1 hr. of stirring 4 drops of diluted ammonia solution is added to maintain the pH at 4. The
second solution is prepared using 200 g of Zn(CH3COO)22H2O dissolved in deionized water. This
solution is stirred for 1½ hrs. at 50C. Finally, the starting and second solutions are mixed and stirred
for 1½ hrs. The final sol is poured into the plastic mould and covered with aluminium foil. The sols
are aged at 40C for 48 hrs.
After 2 days, few holes are made in the aluminium foil and kept at 40C for 2-7 days in drying oven.
The number of holes are gradually increased thereafter, and dried for another 10 or 15 days. The
samples are heat treated in PID controlled furnace, with the following scheme of heat treatment.
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
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Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
45
In the present work, five samples with different weight fraction of ZnO nanoparticles embedded into
the SiO2 matrix are synthesized by sol-gel process. The concentrations (in wt%) of the different
components zinc acetate dihydrate, ethanol and TEOS for the five samples are present in Table 1.
Table 1. Formulation and proportions of the samples.
Sample
Tetraethyl orthosilicate
Pure ethanol
Zinc acetate dehydrate
ZS1
10 ml
10 ml
0.200 g
ZS2
10 ml
10 ml
0.400 g
ZS3
10 ml
10 ml
0.600 g
ZS4
10 ml
10 ml
0.800 g
ZS5
10 ml
10 ml
1 g
Fig. 1. XRD patterns of ZS1 xerogel.
Results and discussion. Fig.1 shows the XRD patterns of ZS1 xerogel heat treated at different
temperatures 120, 300 and 500C. In the XRD patterns of ZS1 xerogel, the absence of any sharp peak,
clearly indicates the amorphous nature of the synthesized nanocomposite at all temperatures.
FE-SEM images. The FE-SEM images of ZS1 and ZS4xerogels are provided in Fig. 2 and 4.
respectively. The EDS spectrum of the ZS1 and ZS4 xerogels are presented in Figs. 3 and 5. Fig. 2
shows ZnO nanoparticles are embedded in the SiO2 matrix at only few places due to less (0.200 g)
ZnO in the nanocomposite. When the amount of ZnO is increased, more interstitial gaps are occupied
by ZnO nanoparticles which is clearly evident from the FE-SEM image Fig.4. This fact is supported
by the EDS images 3 and 5 respectively.
10
20
30
40
50
60
70
80
Position [2
Theta]
Intensity
(a.u.)
120C
300C
500C
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
46
Fig. 2. FE-SEM of the ZS1. Fig. 3. The EDS spectrum of the ZS1.
Fig. 4. FE-SEM of the ZS4. Fig. 5. The EDS spectrum of the ZS4.
FT-IR spectrum. Fig.6 shows the FT-IR spectrum of ZS1 xerogel samples calcined at 120C, 300C
and 500C. In the FT-IR spectrum the broad bands at 3456 and 1633 cm
-1
can be attributed to the
stretching and bending vibrational modes of OH in molecular water and the SiOH stretching of
surface silanols hydrogen-bonded to molecular water respectively [8], [9]. A broad and strong band
is observed at 1086 cm
-1
that is assigned to asymmetric stretching vibration of siloxane group
SiOSi. In addition, weak band located at 962 cm
-1
is due to ZnOSi stretching vibration
[10]. A medium intensity band is noticed at 801 cm
-1
that is due to deformation of SiOSi bond.
A strong peak at 464 cm
-1
is caused by the OSiO bending vibration [11].
TG-DTA curves. The TG-DTA curves of ZS1 xerogel recorded in the range of 100 to 1100C are
illustrated in Fig. 7.The TGA curve can be roughly divided into four stages. In stage 1 there is a sharp
decrease in the weight of the sample when it is heated from room temperature up to about 160C and
a weight loss of 17% which corresponds to the loss of physical water. In stage 2 very low weight loss
0.75% is observed between 160 and 360C. Stage 3 occurs between 360 and 600C with weight a
loss of nearly 2%. Stage 4 occurs from 600C up to 1020C and corresponds to a very small weight
loss of about 1.50%. The weight loss of stages 2, 3 and 4 are associated both with the removal of the
organic groups and with evaporation of water formed from polycondensation reactions [12]. The
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
47
DTA analysis shows a sharp exothermic peak around 530C is the result of progressive
decomposition of organic matter [13]. The sharp endothermic peak around 170C is primarily due to
the removal of physically bound water. The small exothermic peak about 950C can be attributed to
further removal of residual organic matters.
Fig. 6. FT-IR spectrum of ZS1 xerogel samples.
Fig. 7. TG-DTA curves of ZS1 xerogel.
Summary. ZnO doped SiO
2
monolithic nanocomposite xerogels are synthesized successfully via sol-
gel method. It has been observed that an ageing period of 2 days are optimum and a very slow
controlled rate of evaporation for the first 7-10 days are the most essential factors in producing crack-
free monolithic xerogels. The amorphous natures of the xerogel are confirmed by XRD patterns. The
FE-SEM images clearly show the ZnO nanoparticles embedded into the SiO
2
matrix. The FT-IR
spectrum yields necessary information about the presence of the expected functional groups belonging
4000
3500
3000
2500
2000
1500
1000
500
Wave
%Transmi
120
C
300
C
500
C
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
48
to the ZnOSiO
2
nanocomposites. The TGA and DTA analysis provide the details of various stages
of internal changes happening in the xerogels during heat treatment like removal of bound water,
removal of organic matter etc.
References
[1] Fu Z.P., Yang B.F., Li L. An intense ultraviolet photoluminescent in sol-gel ZnO-
SiO
2
nanocomposites. J. Phys. Condens. Mater., Vol. 15 (2003) 2867-2873.
[2] Mo C.M., Li Y.H., Liu Y.S., Zhang Y. and Zhang L.D. Elemental effect of
photoluminescentinassembliesofnano-ZnO particles/silica aerogels. J. Appl. Phys., Vol. 83 (1998) 4389-
4391.
[3] Chakrabarti, S., Ganguli, D. and Chaudhuri, S. Excitonic and defect related transitions in ZnO-
SiO
2
nanocomposites synthesized by sol-gel technique. Phys. Status Solidi A, Vol. 201 (2004) 2134-
2142.
[4] Abdullah, M., Shibamoto, S. and Okuyama, K. Synthesis of ZnO/SiO
2
/nanocomposites emitting
specific luminescence colours.Opt. Mater. Vol. 26 (2004) 95-100.
[5] Mikrajuddin Iskandar, F., Okuyama, K. and Shi, F.G. Stable photoluminescence of zinc oxide
quantum dots in silica nanoparticles matrix prepared by the combined sol-gel and spray drying
method. J. Appl. Lett., Vol. 89 (2001) 6431-6434.
[6] Cannas, C., Mainas, M., Musinu, A. and Piccaluga, G. ZnO-SiO
2
nanocomposites obtained by
impregnation of mesoporous silica. Compos. Sci. Technol., Vol. 63 (2003) 1187-1191.
[7] Ma, J.G., Liu, Y.C., Xu, C.S., Liu, Y.X., Shao, C.L., Xu, H.Y., Zhang, J.Y.,Lu, Y.M., Shen D.Z. and
Fan, X.W. Preparation and characterization of ZnO particles embedded in SiO
2
matrix by reactive
magnetron sputtering. J. Appl. Phys., Vol. 97 (2005) 103509-103515.
[8] Niu, R., Cui, B., Du, F., Chang, Z. and Tang, Z. Synthesis and characterization of Zn-B-Si-O
nano-composites and their doped BaTiO
3
ceramics. Mater. Res. Bull., Vol. 45 (2010) 1460-1465.
[9] Hayri, E.A., Greenblatt, M., Tsai, M.T. and Ptsai, P. Ionic conductivity in the M
2
O-P
2
O
5
-SiO
2
(M=H, Li, Na, K) system prepared by sol-gel methods. Solid State Ionics, Vol. 37 (1990) 233-277.
[10] Djouadi, D., Chelouche, A., Aksas, A. and Sebais, M. Optical properties of ZnO/silica
nanocomposites prepared by sol-gel method and deposited by dip-coating technique. Phys. Procedia,
Vol. 2 (2009) 701-705.
[11] Xiang, W., Wang, Z., Yang, Q. and Zhao, W. Preparation of sodium borosilicate transport
bulk gel. J. Mater. Sci. Technol., Vol. 12 (1996) 303-307.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
49
DC Conductivity and Dielectric Studies on Fe Concentration Doped LiIAgI
B
2
O
3
Glasses
K. Sreelatha
1,a
, K. Showrilu
1
, V. Ramesh
2
1 Dept. of Physics, Ch. S. D. St Theresa’s (A) College for Women, Eluru, W.G. Dtm. Andhra Pradesh, India
2
Dept. of Physics, Rama Chandra College of Engineering, Vellore, Tamil Nadu, India
a srilatha.prathap@gmail.com
DOI 10.2412/mmse.79.18.548 provided by Seo4U.link
Keywords: DC conductivity, dielectric properties of LiIAgIB
2
O
3
glass system.
ABSTRACT. The conductivity of LiIAgI mixed glasses has been the subject of extensive investigation in recent years
as a quest for new solid electrolytes with super ionic properties due to vast applications. The silver / lithium ions
surrounded by iodide ions diffuse very rapidly and are the main contributors of the conductivity in the glasses. On the
other hand, the silver ions interlocked with the oxide glass network are almost immobile and contribute poorly to the
conductivity. Further, when these glasses are doped with multivalent transition metal ions like iron, mixed electronic and
ionic, pure electronic or pure ionic conduction is expected depending upon the composition of the glass constituents. The
changes in conduction mechanism that take place with the varied oxidation states of iron ions in the glass network and
the role of silver and lithium ions in this process is observed by a systematic study on DC conductivity and dielectric
properties (viz., dielectric constant, loss and AC conductivity over a wide range of frequency and temperature) of LiI
AgIB
2
O
3
glasses mixed with varied concentrations of Fe
2
O
3
from 0 - 2.0 mol %.
Introduction: A study of the electrical properties of the glasses is of considerable importance because
of the insight it gives into the conduction mechanism process-taking place in them. In fact, the
electrical properties of the glasses are largely controlled by the structure, composition, and the nature
of the bonds of the glasses. The investigation of the changes in the electrical properties of glasses
with controlled variation of chemical composition, doping etc., is of considerable interest in the
application point of view.
Among various transition metal ions, the iron ions are considered as effective and useful dopant ions
in the conducting glass materials owing to the fact that they exist in different valence states with
different coordination simultaneously in the glass network. Hence, the connection between the state
and the position of the iron ion and the electrical properties of the host glass containing highly mobile
ions like Ag
+
and Li
+
is expected to be highly interesting. Further, dielectric measurements on ionic
materials also give useful information about dynamical processes involving ionic motion and polaron
transfer. It is known that the conductivity of glassy materials is frequency dependent, so that the
diffusivity of the mobile ions is not entirely characterized by the single steady state parameter σ
DC
quantifying DC conductivity.
DC Conductivity. Fig. 1 represents the variation of (σ
DC
T) with 1/T for LiIAgIB
2
O
3
glasses doped
with different concentrations of Fe
2
O
3
. The plots clearly indicate that DC conductivity obeys
Arrhenius relation. In the concentration range of investigation of Fe
2
O
3
, the measured conductivities
are found to vary in the range 10
6
to10
3
Ohm
1
cm
1
in the high temperature region. The fig: further
indicates the deviations in linear plots (at T = θ
D
/2, i.e., half of the Debye temperature).The activation
energy evaluated from these graphs in the high temperature region is found to decrease with increase
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
50
in the concentration of Fe
2
O
3
up to 0.9 mol % and there after it is found to increase (inset of Fig.1
and Table 1). Fig. 2 presents isotherms of DC conductivity with the concentration of Fe
2
O
3
; the
conductivity is increased at faster rates with increase in the concentration of iron ions up to 0.9 mol %
and then it is decreased for further increase of iron ion content.
Fig. 1 Variation of (σ
DC
T) with 1/T for LiI-AgI-B
2
O
3
:Fe
2
O
3
glasses. Inset represents the variation of
activation energy with the concentration of Fe
2
O
3
.
Fig. 2 DC conductivity isotherms of LiI-AgI-B
2
O
3
: Fe
2
O
3
glasses Inset shows the variation of
conductivity (at 623 K)with the activation energy.
1.55 1.68 1.81 1.94 2.07 2.20
0.2
0.4
0.6
0.3 0.8 1.3 1.8
Conc. Fe
2
O
3
(mol%)
A.E. (eV)
F
3
F
9
F
20
F
6
F
15
F
12
10
-3
10
-7
10
-5
1/T (10
-3
, K
-1
)
dc
T (
W-
cm)
-1
K
0.3 0.6 0.9 1.2 1.5 1.8
350
o
C
280
o
C
230
o
C
Zone - I
Zone - II
0.3 0.4 0.5 0.6
A.E. (eV)
dc
(
W-
cm)
-1
10
-6
10
-3
dc
(
W-
cm)
-1
10
-3
10
-5
10
-7
Conc. Fe
2
O
3
(mol %)
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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51
Table 1. Summary of data on conductivity studies of LiIAgIB
2
O
3
: Fe
2
O
3
glasses.
Glass
W
DC
(eV)
W
H
(eV)
J
(eV)
W
ac
(eV)
N(E
F
)
( x 10
20
eV
-1
/cm
3
)
A.E. for
dipoles
(eV)
F
3
0.612
0.365
0.091
0.489
1.39
2.77
F
6
0.466
0.274
0.069
0.392
1.74
2.31
F
9
0.301
0.180
0.045
0.261
3.12
2.28
F
12
0.376
0.219
0.055
0.326
2.52
2.57
F
15
0.43
0.257
0.064
0.301
2.06
2.74
Dielectric properties. The dielectric constant ε and loss tanδ at room temperature (≈30
o
C) of pure
LiIAgIB
2
O
3
glasses at 100 kHz are measured to be 12.4 and 0.005,respectively. The temperature
dependence of ε′ of the glasses containing different concentrations of Fe
2
O
3
at 1 kHz is shown in
Fig. 3 and at different frequencies of glass F
9
is shown as the inset of the same figure. The value of ε
is found to exhibit a considerable increase at higher temperatures especially at lower frequencies; the
rate of increase of ε′ with temperature is found to be the highest for the glass doped with 0.9 mol %
of Fe
2
O
3
. The temperature dependence of tan δ of all the glasses measured at a frequency of 10 kHz
is presented in Fig. 4. In the inset of the same figure, the variation of tan δ for one of the glasses (glass
containing 0.9 mol % of Fe
2
O
3
), at different frequencies is presented. These curves have exhibited
distinct maxima; with increasing frequency the temperature maximum shifts towards higher
temperature and with increasing temperature the frequency maximum shifts towards higher
frequency, indicating the dielectric relaxation character of dielectric losses of these glasses. From
these curves, the effective activation energy, W
d
, for the dipoles is calculated for different
concentrations of Fe
2
O
3
and presented in Table 1; the activation energy is found to be the lowest for
the glass F
9
and the highest for the glass F
3
.
The ac conductivity σ
ac
is evaluated at different temperatures from the values of dielectric constant
and loss using the conventional equation and its variation with 1/T for all the glasses at 100 kHz is
presented in Fig. 5.
Fig. 3. A comparison plot of variation of dielectric constant with temperature at 1 kHz for LiI-AgI-
B
2
O
3
loss with temperature concentrations of Fe
2
O
3
. Inset shows the variation of dielectric constant
with temperature at different frequencies for the glass F
9
.
10
20
30
40
50
0 50 100 150 200 250 300 350
Temparature (
o
C)
e
'
10
20
30
40
50
0 100 200 300
Temparature (
o
C)
e'
1 kHz
10 kHz
100 kHz
Fig. A comparison plot of variation of dielectric constant with temperature at 1 kHz for LiI-
AgI-B
2
O
3
glass doped with various concentrations of Fe
2
O
3
. Inset shows the variation of
dielectric constant with temperature at different frequencies for the glass F
9
.
F
3
F
9
F
20
F
6
F
15
F
12
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
52
Fig. 4. A comparison plot of variation of dielectric loss with temperature at 10 kHz for LiI-AgI-B
2
O
3
glasses. Inset shows the variation of dielectric loss with temperature at different frequencies for the
glass F
9
.
Similar to that of DC conductivity, σ
ac
is also found to be the highest for the glasses containing 0.9
mol % of Fe
2
O
3
at any temperature. The variation of AC conductivity with temperature exhibited a
plateau up to 110
o
C and thereafter (beyond the relaxation region) it is increased rapidly exhibiting
the highest rate of increase for the glass F
9
. From these plots, the activation energy for the conduction
in the high temperature region over which a near linear dependence of log σ
ac
with 1/T could be
observed is evaluated and presented in the Table 1.
Discussion. B
2
O
3
is a well known network former, participates in the network forming with BO
3
and
BO
4
structural units. AgI and LiI do act as modifiers like any conventional modifiers and create
bonding defects. In some of the recent investigations it has also been reported that Ag
+
and Li
+
ions
in oxy salt glass matrices experience mixed oxygeniodine coordination and do not induce any
defects in the glass network [1], [2], [3]. According to this model AgI and LiI mainly act to expand
the glass network, which leads to the increase in the accessible volume for the fraction of mobile Ag
+
and Li
+
ions that act as modifiers. In fact, a general relation between the network expansion and the
conductivity enhancement for a large variety of alkalihalide mixed oxide glasses has been reported
[4]. Iron ions are expected to exist mainly in Fe
3+
state in LiIAgIB
2
O
3
glass network. However,
regardless of the original oxidation state of the iron in the starting glass batch, the final glass contains
both Fe
3+
and Fe
2+
ions [5].
Fe
3+
ions are expected to occupy both tetrahedral and octahedral positions in the glass network.
Nevertheless, the fourfold coordination of Fe
3+
is observed to be more common than the six fold
coordination in many of the glasses [6]. When a plot is made between log σ
DC
vs activation energy
for conduction, a near linear relationship is observed (inset of 2); this observation suggests that the
conductivity enhancement is also related to the thermally stimulated mobility of the charge carriers
in the high temperature region. The maximal effect observed at x = 0.9 mol% in the isotherms of DC
conductivity suggests that there is a changeover of conduction mechanism at this point.
Additionally, as has been mentioned earlier, the conductivity enhancement with temperature for a
given composition of the glass suggests the contribution of ionic transport to the conduction in
addition to the polaron hopping. The decrease in activation energy and increase in conductivity with
iron ion content up to 0.9 mol % (Figs. 1 - 2) may be due to higher rate of polaron hopping
(Fe
2+
↔Fe
3+
) and ionic transport. Though electronic and ionic conductivities are not separated but the
observed trend of increase of conductivity and decrease of activation energy (for the glass containing
Fe
2
O
3
below 0.9 mol %) (zoneI) and decrease of conductivity and increase of activation energy (for
0.00
0.04
0.08
0.12
0.16
0.20
0 50 100 150 200 250 300 350
Temperature (
o
C)
Tan
d
Fig. 4. A comparison plot of variation of dielectric loss with temperature at 10 kHz for LiI-AgI-
B
2
O
3
glasses doped with various concentrations of Fe
2
O
3
. Inset (a) shows the variation of
dielectric loss with temperature at different frequencies for the glass F
3
.
0
0.03
0.06
0.09
0 100 200 300
Temperature (
o
C)
Tan
d
1 kHz
10 kHz
100 kHz
F
3
F
9
F
20
F
6
F
15
F
12
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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53
the glass containing Fe
2
O
3
beyond 0.9 mol %) (zoneII) indicates different conduction mechanisms
on the two sides of this composition. This type of composition dependence of isothermal conductivity
is quite conventional in the glasses containing mobile monovalent cations (like Li
+
and Ag
+
) and
transition metal ions like iron.
To explore the nature of the hopping conduction in LiIAgIB
2
O
3
: Fe
2
O
3
glasses a graph between
log
DC
(measured at 623 K) and the activation energy W
DC
is plotted in the inset of Fig. 2. The graph
obtained is a straight line. From the slope of this curve, the value of 1/kT is obtained and the
temperature T is estimated. The value of T is found to be 615 K, which is very close to the actual
temperature. In small polaron hopping model (SPH Model), the polaron bandwidth J for adiabatic
case is given by
J > (2kTW
H
/π)
1/4
(hν
0
/ π)
1/2
(1)
The polaron bandwidths are also calculated from the relation:
J = J
0
exp(–αR)
where J
0
= W
H(min)
/4 and are furnished in Table 1.
From this table, it may be noted that J for all the glasses satisfies the Eq.(1) and hence the conduction
may be taken as adiabatic which means there is noncompatibility between the hopping rate of
polaron and phonon frequency. According to a more general polaron hopping model (where W
D
> 0)
it is the optical multi phonon that determines DC conductivity at high temperatures, while at low
temperatures, charge carrier transport is via an acoustical phononassisted hopping process.
With the gradual increase of Fe
2
O
3
up to 0.9 mol % in the glass network, the values of ε
'
, tan δ and
σ
ac
are found to increase at any frequency and temperature and the activation energy for AC
conduction are observed to decrease. This observation indicates an increase in the space charge
polarization owing to the enhanced degree of disorder in the glass network due to the presence larger
proportions of Fe
2+
ions that act as modifier. The dielectric relaxation effects exhibited by these
samples can safely be attributed to association of divalent iron with a pair of I
or O
ions, in analogy
with the mechanismassociation of divalent positive ion with a pair of cationic vacancies in
conventional glasses, glass ceramics and crystals. The increase in the breadth and the intensity of the
relaxation peaks and (for the samples F
3
to F
9
) supports the view point that there is a higher
concentration of divalent iron ions and also Li
+
and Ag
+
ions in these glasses that acts as modifiers.
The lower values of activation energy for these samples suggest an increasing degree of freedom for
dipoles to orient in the field direction.
The variation of the exponent (obtained by plotting log σ(ω) vs ω) is found to be the highest for the
glass F
9
(inset of Fig. 5). Such increase suggests that dimensionality of conduction space is the highest
for this glass [7], [8].
The AC conductivity in the low temperature region (near plateau region) can be understood based on
quantum mechanical tunnelling model. Based on Austin and Mott’s model (quantum mechanical
tunnelling model) [9], the density of defect energy states near the Fermi level, N(E
F
), at nearly
temperature independent region of the conductivity (low temperature) is evaluated using:
σ(ω) = Π/3 e
2
KT [N(E
F
)]
2
α
5
ω [ ln(ν
o
/ω) ]
4
(2)
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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54
where α is the electronic wave function decay constant,
ν
0
is the phonon frequency and presented in table 1.
The value of N(E
F
) i.e., the density of defect energy, is found to increase gradually from the sample
F
3
to F
9
, indicating a growing degree of disorder with increase in the content of Fe
2
O
3
up to 0.9 mol
% in the glass network.
Summary. LiIAgIB
2
O
3
glasses mixed with different concentrations of Fe
2
O
3
(ranging from 0 to
2.0 mol %) were prepared. DC. conductivity and dielectric properties have been investigated. DC
conductivity is increased up to 0.9 mol % of Fe
2
O
3
and beyond that the conductivity is found to
decrease. The analysis of the DC conductivity results indicated that there is a mixed conduction (both
ionic and electronic) and the ionic conduction seems to prevail over polaron hopping in the glasses
containing Fe
2
O
3
more than 0.9 mol %.
References
[1] K.K. Olsen and J. Zwanziger, Solid State Nucl. Mag. Reson., Vol. 5 (1995), p. 123, DOI
10.1016/0926-2040(95)00035-O
[2] K.K. Olsen, J. Zwanziger, P. Hertmann, C. Jager, J. NonCryst. Solids, Vol. 222 (1997), p. 199,
DOI 10.1016/S0022-3093(97)90114-9
[3] E.I. Kamitsos, J.A. Kaputsis, G.D. Chryssikos, J.M. Hutchinson, A.J. Pappin, M.D. Ingram, J. A.
Duffy, Infrared study of AgI containing superionic glasses, Phys. Chem. Glasses, Vol. 36 (1995), p.
141.
[4] J.D. Wicks, L. Borjesson, G. BushnellWye, W.S. Howells, R.L. McGreevy, Phys. Rev. Lett.,
Vol. 74 (1995), p. 726, DOI 10.1103/PhysRevLett.74.726
[5] G.K. Marasinghe, M. Karabulut, C.S. Ray, D.E. Day, C.H. Booth, P.G. Allen, D.K. Shuh, Ceram.
Trans., Vol. 87 (1998), p. 261.
[6] G.K. Marasinghe, M. Karabulut, C.S. Ray, D.E. Day, C.H. Booth, P.G. Allen, D.K. Shuh, J. Non
Cryst. Solids Vol. 249 (1999), p. 261.
[7] D.L. Sidebottom, Dimensionality Dependence of the Conductivity Dispersion in Ionic Materials,
Phys. Rev. Lett. Vol. 83 (1999), p. 983.
[8] S. Bhattacharya, A. Ghosh, Conductivity spectra in fast ion conducting glasses: Mobile ions
contributing to transport process, Phys. Rev. B, Vol. 70 (2004), 172-203.
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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55
Conductivity, Morphology and Thermal Studies of Polyvinyl Chloride (PVC)-
Lithium Nitrate with Cadmium Oxide (CdO)
P. Karthika
1, a
, R. Gomathy
2
, P.S. Devi Prasadh
3, b
1 Department of Physics, SNS College of Engineering, Coimbaore, India
2 Department of Physics, Dr. Mahalingam College of Engineering & Technology, Pollachi, Coimbatore, India
3 School of Advanced Sciences, VIT University, Vellore, Tamilnadu, India
a pkarthikaa@gmail.com
b psdprasadh@gmail.com
DOI 10.2412/mmse.31.97.961 provided by Seo4U.link
Keywords: PVC, LiNO
3
, CdO, conductivity, SEM, TGA.
ABSTRACT. High ionic conductivity of polymeric system is important in polymer research. Solvent cast technique is
used to formulate the polyvinyl Chloride (PVC) Lithium Nitrate (LiNO
3
) Cadmium Oxide (CdO) system. Nature of
complexation and concentration of various ionic species are important to understand the conductance mechanism.
Conductivity studies provided with the help of ac impedance analyser. Morphology behaviours of polymer electrolytes
have been studied using SEM. The thermal properties of polyvinyl chloride(PVC) Lithium Nitrate (LiNO
3
) Cadmium
Oxide (CdO) by Thermo Gravimetric Analysis (TGA) gives rise the information on the thermal stability of polymer
electrolytes.
Introduction. Now a days, researchers have very much interested in studying the ionic conductivity
at ambient temperature due to their unique performance in high power rechargeable lithium battery,
which can be used in laptops and even electric vehicles and other portable electronic equipment. The
preparation of polymer electrolytes with high conductivity, good mechanical strength and thermal
stabilities are interest due to the role of polymer electrolytes in lithium batteries, electro chromic
windows, sensors and fuel cells etc. [1]. In our everyday life, polymers are widely used due to their
fascinating and extraordinary characteristics. To replace the conventional materials in terms of
strength, stability and toughness they are found. Since the beginning of plastic industry, it is observed
that blending yields materials with superior features of the individual components. Blending of
polymers provide new materials which combine the useful property of all constituents.
Technological interest of polymer electrolytes are due to their possible application as solid
electrolytes in various electrochemical devices such as energy conversion units, electro-chromic
display devices, photo chemical solar cells and sensors. The polymer electrolytes in lithium batteries
are most widely studied among the various applications, A polymer electrolyte will function as a
separator as well as an electrolyte in a secondary battery. Studies on polymer electrolytes have great
intention to explain the enhancement mechanism of conductivity. Various ionic species’
concentration are important to understand the overall mechanism of conductivity, The structural and
morphological behaviours of polymer electrolytes have been studied by SEM. In this work, polymer
electrolytes are prepared by solution casting technique which contained polyvinyl chloride (PVC) as
a host polymer and lithium nitrate(LiNO
3
) as a salt. The nano filler CdO added with various
proportion to these polymer electrolytes to get nanocomposite polymer electrolytes (NCPE). Then,
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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56
the thermal characteristics have done by Thermo Gravimetric Analysis (TGA). Conductivity studies
done with the help of ac impedance analyzer.
Experimental Techniques: Chemicals with AR/BDH grade were purchased from Aldrich, Merck
companies and used as such, Tetra Hydro Furan (THF) used after distillation only. Polymer: Poly
(vinyl chloride), Polyelectrolyte: Lithium nitrate(LiNO
3
) , Solvent: Tetra Hydro Furan (THF), Nano
filler: Cadmium Oxide (CdO). The polymer salt complex prepared by solvent casting technique. It
was very simple and most widely used technique for preparation of thick films. Polymer electrolyte
prepared by solvent casting technique. The appropriate quantity of PVC & LiNO
3
dissolved in Tetra
hydro furan. After a complete dissolution of polymer and salt, metallic filler, CdO added and stirred
for 4 5 hours. A homogeneous solution obtained after stirrer and resulting solution poured on to a
glass plate and THF allowed evaporating in air at room temperature in dust free atmosphere. The
films dried for another one day to remove any trace of THF. The concentration of CdO varied and
films were prepared.
Result and Discussion:
AC Impedance Characteristics. PVC composite with LiNO
3
studied in order to see the effect of
their addition to polymer electrolyte conductance. This ionic conductivity determined by ac
impedance analysis at room temperature say around 302K. Various combination of the three
components PVC - LiNO
3
- CdO were Compared and one of them shown in Fig. 1 (e). The ionic
conductivity of polymer electrolyte can be calculated using the formula given by:
σ
ac
= Thickness/(Area)×(Resistance) = s/cm.
Ionic conductivity of polymer electrolyte changed due to concentration of conducting species and
their mobility. The conductivity increases against the concentration of CdO, it can be seen that PVC
LiNO
3
exhibited the lowest conductivity as 5.27 × 10
- 10
s/cm. The effect of concentration of nanofiller
CdO on the ionic conductivity of the films which showed that the increase in concentration of CdO,
ionic conductivity also increased which may be due to increase in the number of mobile ions in the
solid polymer electrolytes. A highest value 6.33 × 10
-6
s/cm was obtained at 10 Wt % of CdO. The
addition of nanofiller with the polymer electrolyte system made the system be more amorphous and
promoted more free lithium ions from the inorganic salt of LiNO
3
[1].
Fig. 1. Impedance Plot for PVC + LiNO3 + CdO (10 Wt ).
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57
Increase of CdO content reduced the crystallinity of composite polymer electrolyte. A polymer chain
in the amorphous phase was more flexible which increased segmental motion of polymer. Oxygen
concentration enhanced the conductivity of electrolyte [2]. The lithium (Li
+
) ion moved like a
gaseous molecule in free volume model where Li
+
transferred to coordinating sites in the same
polymer chain. The segmental motion of increased the ionic conductivity. When smaller size
nanofiller added to polymer electrolytes may be promoted amorphous region there by enhancing the
transportation of ions in membrane. Based on Lewis acid base interaction, ceramic filler influenced
the ionic conductivity of polymer electrolyte due to interactions between the surface groups of
ceramic particles and lithium salt [3]. Li
+
served as a strong Lewis acid where as polymer and filler
CdO served as a Lewis base centres. Therefore, the polymer Li
+
cation and filler Li
+
cation
interactions may be widely used to explain the polymer salt complex interaction [4]. This created
structural modification, which may be acted as a cross linking centres for the polymer segment and
the salt anions. The Lewis base interaction centres lowered ionic coupling there by salt dissociation
promoted via a sort of ion ceramic complex formation. The mentioned two effects enhanced the
conductivity of nanocomposites. Oxygen and OH surface groups on CdO grains interacted with
cations and anions based on Lewis acid base and promoted additional site creating favourable high
coordinating pathways in the vicinity of grains for the migrations of ions [5]. It enhanced the mobility
for migrating ions.
SEM Analysis. It is noticed from the figure 2a that the rough surface with streaks. PVC LiNO
3
complex with CdO(3 Wt %) showed maximum number of pores of random shapes giving rise to
increase in conductivity of this sample. There are two possible ways for formation, first one was the
evaporation of solvent and second one was the casting of the film. Plasticizer occupied the pores,
which acted as the tunnel for ionic transport. It was observed that pores in 3 Wt % disappeared when
CdO concentration increased to 5 Wt %. This might be occurred due to fill the pores of CdO there by
promoting amorphicity through plasticizing effect of filler. In Fig. 2. (b), it was noticed that the
appearance of number of uniform tracks of few micrometer size along with reduced size which was
responsible for the enhancement o ionic conductivity of PVC- LiNO
3
CdO ( 8 Wt %). The distinct
spherules by dark boundaries showed in solid polymer electrolyte with CdO 10 Wt %. This was due
to amorphous phase [10]. Thus, SEM study supported the conclusions drawn through ac conductivity
studies.
a) b)
Fig. 2. (a) SEM Micrograph for PVC + LiNO
3
, (b) SEM Micrograph for PVC + LiNO3 + CdO
(8 Wt %).
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58
TGA/DTA analysis. Based on the TGA graph, the percentage total weight loss of sample can be
calculated through the direct subtraction of the percentage residue from 100 Wt %. Since this graph
was plotted as weight as temperature. In Fig. 3. (a), the TGA/DTA trace of pure PVC, the weight
losses corresponding to various temperature regions were shown . It showed that six stages of
degradation. The first stage of degradation occurred in region C 250 ˚ C with weight loss of
1.54 % which ascribed to the removable of unsaturation of PVC [5]. The unbroken double bonds of
vinyl chloride monomers presented in some of PVC macromolecules as a consequences of the
disproportionate chain termination reaction during polymerization and called unsaturation reaction.
These double bonds would be broken at the first stage of degradation and would be led to monomers
evaluation as observed in the case of PMMA [5]. In pure PVC + LiNO
3
,1
st
degradation occurred at
0 ̊C-150 ̊C with 16.59% weight loss which was very much higher than Pure PVC. There was gradual
then faster degradation around 150 ̊C that indicated the thermal stability of complexes initially lower
than PVC. Around 250 ̊C - 315 ̊C, there was 40.87% weight loss compared with PVC, then the
thermal stability was higher. Around 315 C – 445 ̊C, 6.22% weight loss and around 445 ̊C 555 ̊C,
17.95% weight loss occurred , both indicated higher thermal stability. Thermally irreversible state
reached by following degradations such as around 555 ̊C 610 ̊C, 2.86% weight loss, 610 ̊C – 770 ̊C,
7.704% weight loss and 770 ̊C – 1050 ̊C, 1.85% weight loss. PVC + LiNO
3
initially exhibited lower
thermal stability when compared with PVC & then above 150 ̊C showed higher thermal stability.
Fig. 3. (a) TGA DTA plot for pure PVC.
Summary. Using solvent casting technique, the nanocomposite polymer electrolyte prepared and in
order to understand the role of nanofiller on the thermal and electrical properties, the nanofiller of
different concentration of CdO added to PVC - LiNO
3
. Ionic conductivity of polymer electrolyte
depends on the concentration of conducting species & their mobility .The addition of nano-fillers
enhanced the ionic conductivity. SEM confirmed the plasticizing action of CdO. TG-DTA provided
the information with regard to their thermal stability, crystallinity & other thermal parameters.
References
[1] S. Ramesh and A. K. Arof, Strutural, Thermal and Electrochemical Cell Characteristics of Poly
(Vinyl Chloride)-Based Polymer Electrolytes, Journal of Power Sources, Vol. 99, No. 1-2, 2001, pp.
41-47. DOI 10.1016/S0378-7753(00)00690-X
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59
[2] Sejal Shah, Dolly Singh, Anjum Qureshi, N L Singh, V. Shrinet, Dielectric properties and surface
morphology of proton irradiated feuic oxalates dispersed PVC films, Indian J. Pure & Appl. Phys, 46
(2008), 439-442. link: http://hdl.handle.net/123456789/1638
[3] Azizan Ahmad, Mohd.Yusri Abdul Rahman, Siti Aminah Mohd Noor, Mohd Reduan Abu Bakar,
Preparation and characterization of PVC - Al
2
O
3
-LiClO
4
composite polymeric electrolyte, Sains.
Malays, 38 (4) (2009), 107- 113.
[4] W. Wiec Zorek, J.R. Stevens, Z. Florja Czyk, Composite polyether based solid electrolytes,The
Lewis acid base approach, Solid State Ionics,85(1-4)(1996)67-72. DOI 10.1016/0167-
2738(96)00042-2
[5] F. Croce, L. Persi, F. Ronci, B. Scrosati, Nanocomposite polymer electrolytes and their impact on
the lithium battery technology, Solid State Ionics, 135 (1-4) (2000), 47-52, DOI 10.1038/28818
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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60
Electrochemical Detection of Ascorbic Acid Using Pre-treated Graphite
Electrode Modified with PAMAM Dendrimer with Poly (Nile Blue)
C. Lakshmi Devi
1
, J. Jayadevi Manoranjitham
1
, S. Sriman Narayanan
1, a
1 University of Madras, Department of Analytical Chemistry Guindy Campus, Chennai, Tamil Nadu, India
a sriman55@gmail.com
DOI 10.2412/mmse.1.74.381 provided by Seo4U.link
Keywords: electro polymerization, pre-treated modified electrode, poly (nile blue), poly (amido amine), ascorbic acid.
ABSTRACT. A new type of PAMAM/PNB modified electrode has been prepared for the electro catalytic oxidation of
ascorbic acid. The PAMAM [poly (amido amine)] dendrimer was synthesized based on EDA (ethylenediamine) core in
generation (0.5). The graphite electrode is pre-treated by using H
2
SO
4
. The PAMAM (G0.5-NH
2
) dendrimer is
polymerized on the pre-treated electrode followed by the electrochemical polymerization of nile blue (NB) over the
PAMAM coated electrode. The PAMAM/PNB modified electrode was electrochemically characterized by CV. The cyclic
voltammetry behaviour of PAMAM/PNB modified electrode in 0.1M PBS of pH 7 at scan rate of 50mVs
-1
showed a pair
of redox peaks. The utility of the modified electrode towards the electro catalytic oxidation of ascorbic acid was
investigated. It was observed, that the PAMAM/PNB modified electrode showed better electro catalytic oxidation when
compared to bare electrode.
Introduction. Ascorbic acid (AA) is a water-soluble antioxidant and called as vitamin C. Since our
body is unable to synthesize ascorbic acid by its own metabolism, we take the food with rich sources
of AA such as citrus fruits, vegetables, leafy vegetables. The main function of antioxidant is to reduce
the oxidative damage caused by the free radicals, which results in improper functioning of cells as
excess of free radicals results in oxidative stress [1]. Oxidative stress may causes serious health issues
such as damage of normal cells, which leads to cancer, improper protein synthesis, DNA damage etc.
[2]. Insufficient amount of ascorbic acid leads to high blood pressure, stoke cancers, AIDS,
atherosclerosis, gallbladder disease etc. [3]. Therefore, it is very important to detect and quantify AA
in food sources, pharmaceutical compounds. Various methods have been used for determination of
AA among them, electrochemical sensors using conducting polymer dyes have gained much
importance and in the bio analytical science because the polymer consists of more number of
functional groups which helps in enhancing the sensitivity and electro catalytic activity of sensor
device [4]. Some of the early reports where polymer dyes used as sensor for various analyses are poly
nile blue [5], [6], poly neutral red [7], poly brilliant crystal blue [8]. PAMAM dendrimers are
branched three-dimensional macromolecules with covalent micelles, well-defined cavities, high
reactivity and stable compounds used for coating electrodes in order to get physic-chemical properties
[9]. Since dendrimer consists of cavities which helps the dye molecules to adsorb in those cavities
effectively thereby improving the sensitivity of the modified electrode. Here we report a modified
electrode using PAMAM and poly (nile blue) for the determination of AA.
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
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61
Fig. 1. Scheme for fabrication of PGE/PAMAM/PNB electrode.
Experimental
Equipment. The electrochemical experiments were carried out using CHI 400A electrochemical
system (CH instruments USA). Cyclic Voltammetry (CV) was performed using conventional three-
electrode setup with the PAMAM/PNB modified electrode as the working electrode, a platinum
electrode as the counter electrode and standard calomel electrode as the reference electrode. The
solutions were made free from oxygen by purging with pure nitrogen. The parameters for the CV
were -0.6 to -1.2V. Scan rate 50mV s
-1
. pH of the solution was measured using digital pH meter
(Digisun electronics system). All experiments were performed at ambient temperature.
Chemicals and reagents. Graphite electrode (3mm diameter) was purchased from Aldrich.
Ethylenediamine was purchased from Merck. Ascorbic acid and Nile blue were obtained from Cisco
Research Laboratories, India. And all other reagents employed were of analytical grade and used as
received. All the supporting electrolytes (0.1 M) and PBS buffer solution (0.1 M) solution were
prepared in doubly distilled (DD) water.
Poly (amido amine) dendrimer synthesis. Poly (amido amine) dendrimer was synthesized as
reported earlier [10-12]. A round bottom flask (100ml) was taken with the reaction mixture of
Ethylenediamine (0.45 g., 7.49 mmol), methanol (MeOH) (10 mL) and methyl acrylate (5.15 g., 59.8
mmol) and the reaction mixture was stirred for 24 hrs. in nitrogen atmosphere at room temperature.
After 24 hrs. reaction mixture was transferred to rotary evaporator to remove the unreacted methyl
acrylate, which has resulted in an intermediate product bearing four terminal methyl ester groups
(2.98 g., 98.6%). Dissolved 4.93 g. of ethylenediamine in 10 mL methanol was added to the
intermediate product and the reaction mixture was stirred at room temperature for 24 hrs. under
nitrogen, and then the solvent and excess ethylenediamine were removed using rotary evaporator.
This final product G 0.5 PAMAM dendrimer were synthesized by repeating Michael addition and
amidation reaction.
Fabrication of PAMAM/PNB film modified electrode. The base material for preparation of
modified electrode is paraffin impregnated graphite electrode (PIGE). The PIGE was prepared as
reported earlier [13], [14]. The polished end of the PIGE was dipped into 0.5 M H
2
SO
4
solution and
a potential of 1.6 V was applied for 5min to promote the carboxylic acid on the surface of the PIGE
electrode. This is called as pre-treated graphite electrode (PGE). The PGE was immersed into 0.1 M
NaF solution containing 50µL PAMAM dendrimer. The PAMAM dendrimer was electro deposited
to the surface of PGE by applying a potential of 0.6V for 1h. Further, this PGE/PAMAM modified
electrode was dipped into the 0.1M PBS (pH 5) containing 0.5 mM nile blue. The nile blue was electro
polymerized over the surface of PGE/PAMAM modified electrode by applying a potential of -0.6V
to 1.2 V for 20 cycles at a scan rate of 50 mV/s. The resulted PGE/PAMAM-PNB electrode was used
for the electro catalytic oxidation of AA. Fig.1 shows the scheme for fabrication of PGE/PAMAM-
PNB electrode.
Results and discussion
Polymerization on nile blue. The electro polymerization of nile blue (NB) over the surface of
PGE/PAMAM electrode was carried out by applying potential a potential of ‒0.6V to 1.2 V for 20
cycles Fig.2 shows the cyclic voltammograms of electro polymerization of nile blue over the
PEG/PAMAM electrode. The cyclic voltammograms shows two redox couple, the first redox couple
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62
around ‒0.4V is due to the oxidation and reduction of the NB monomers. The second redox peak
around ‒0.1 V is due to the oxidation and reduction of PNB. The peaks at 0.8 V is due to the monomer.
As the polymerization progresses the peaks at ‒0.1 increases indicated the formation of the PNB. The
peak current at ‒0.1V increases for successive cycles due to the growth of the PNB film over the
surface of PGE/PAMAM electrode. Once the polymer film is formed, the PGE/PAMAM-PNB
electrode was dipped into 0.1M PBS of pH 7 solution and scanned at a potential range from ‒0.6V to
1.2V to conform the formation of polymer film.
Fig. 2. Cyclic voltammograms electropolymerization PNB in 0.1 M PBS (pH 5.3) consists of 0.5
mM NB.
Electrochemical determination of ascorbic acid using PAMAM/PNB modified electrode. Under
optimized condition such as pH, different electrolyte, and scan rate (figures not shown) the
PGE/PAMAM-PNB electrode showed a well defined redox peak in PBS of pH7 at a scan rate of
50mV/s. Thus, PBS of pH7 was used for further studies. In order to investigate the application of
PGE/PAMAM-PNB electrode was used for determination AA. Fig. 3 shows the cyclic
voltammogram of bare and modified in absence and presence of 1.6×10
-4
M AA. The bare PIGE
oxidized AA at 0.3V but the PGE/PAMAM-PNB electrode oxidized at a very lower potential of
around 0.2V. Therefore, the PGE/PAMAM-PNB electrode oxidizes AA at very lower potential and
the peak current is high when comparing with bare PIGE. This is due to the presence of PAMAM and
PNB film, which enhances the electrocatalytic activity of the electrode towards oxidation of AA.
Fig.4 shows the cyclic voltammogram response of PGE/PAMAM-PNB electrode on different
concentration of AA. On increasing the concentration of AA, the oxidation current is also increased
linearly.
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63
Fig. 3. CVs of (a) bare, (b) in presence of (1.6X10
-4
M) Ascorbic acid,(c) PAMAM/PNB film-modified
electrode, and (d) in presence of (1.6X10
-4
M) Ascorbic acid, in 0.1 M PBS (pH7) solution; scan rate:
50 mV/s.
Summary. A highly stable electro active PGE/PAMAM/PNB film modified electrode was fabricated
successfully by electro polymerization of NB over PGE/PAMAM electrode. The resulted
PGE/PAMAM-PNB electrode was characterized by Cyclic Voltammetry. Further the PGE/PAMAM-
PNB electrode was used for the electrocatalytic oxidation of AA. The modified electrode was found
to be highly stable, selective and sensitive towards the determination of AA. The proposed
PGE/PAMAM-PNB film-modified electrode has shown a high determination range is 1.6µM to 1666
µM.
Acknowledgements. The authors acknowledge the financial assistance from DST-Inspire fellowship,
New Delhi, India, and Department of Science and Technology for PURSE program in support of this
work.
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65
Morphological Investigation of Small Molecule Solution Processed Polymer
Solar Cells Based on Spin Coating Technique
Liyakath Reshma
1
, Kannappan Santhakumar
2,a
1 School of Electronics Engineering, VIT University, Vellore, Tamil Nadu, India
2 Carbon Dioxide and Green Technologies Centre, VIT University, Vellore, Tamil Nadu, India
a ksanthakumar@vit.ac.in
DOI 10.2412/mmse.42.77.422 provided by Seo4U.link
Keywords: polymer solar cell, small molecule, bulk heterojunction, spin coating, power conversion efficiency.
ABSTRACT. Organic solar cells are one of the best candidates to overcome the traditional energy depletion and energy
pollution, because they use simple processing techniques to fabricate and they are under intense investigation in academic
and industrial laboratories because of their potential to enable mass production of flexible and cost effective devices. Here
we explore an efficient solution-processed polymer bulk heterojunction solar cells based on the combination of a small
molecular donor ((DTS(PTTh2)2) and an acceptor (PC
71
BM ) by using chlorobenzene as a solvent in order to obtain the
mixing morphology through spin coating. PEDOT: PSS was used as a surface modifier to reduce the work function of
the conductors. The molecular aggregations in chlorobenzene solvent were investigated by means of UVvisible spectra
and photoluminescence measurements. The surface morphology of the active layers deposited was examined using atomic
force microscopy. The current densityvoltage (JV) characteristics of the photovoltaic cells were measured under the
illumination by using Oriel 1000W solar simulator and the maximum power conversion efficiency has been reported for
this polymer combination. These results indicate that the spin coating technique can be a viable alternative to the high-
cost and vacuum-deposited ITO for mass production and low cost roll-to-roll based solar cells.
Introduction. The world’s demand for usable energy increases every year, with an expected increase
from 479 trillion joule (505 quadrillion Btu) in 2008 to 730 trillion joule (770 quadrillion Btu) in
2035, an increase of 52 %. In order to meet this demand, non-renewable fossil fuels, mostly coal,
and renewable sources of useful energy will need to be deployed. As fossil fuels will eventually
run out and their use seems to be as the main contributor to the increase of the global greenhouse
effect, more research done on the development and deployment of alternative technologies for
renewable energy production. Sunlight is an abundant and virtually eternally renewable energy
source, with 174 petawatt of power arriving at the earth’s atmosphere and about 89 petawatt is
absorbed by land and water. Even using only a fraction of this enormous amount of power may
significantly meet the world’s growing demand for power. Solar cells, which rely on the
photovoltaic effect, transform sunlight into electricity and in order to successfully utilize solar
power, developing well performing and cost-effective photovoltaic devices is paramount. Solar cells
can be categorized into two different kinds, inorganic and organic ones. The former having current
commercial power efficiency between 15 and 20 %, up to 25 % for more refined silicon cells
and
top lab-scale efficiencies of more than 40 % reached with lab-scale multi-junction devices consisting
of various inorganic semiconductors and the usage of light concentration techniques.
However, the
performance of organic solar cells (or Organic Photovoltaics OPV's) is considerably lower with a
commercial efficiency of about 3 to 5 %
and a current top efficiency of 1 0 . 6 %. Organic electron-
donor/electron-acceptor blends are a key ingredient of “plastic” photovoltaic devices, whose
development raises an ever-increasing scientific interest due to their low cost, easy production process
© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license
http://creativecommons.org/licenses/by-nc-nd/4.0/
Mechanics, Materials Science & Engineering, July 2017 ISSN 2412-5954
MMSE Journal. Open Access www.mmse.xyz
66
and mechanical flexibility. Thus, OPV research has taken a new direction in exploring the uses of
different materials [1]. Over the last two decades, the efficiency of these devices has improved