Indian Journal of Pure and Applied Physics

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Volume 46

Number 6

 JUNE 2008

CODEN: IJOPAU 46 (6) 363-458

ISSN: 0019-5596

 

Special Issue on Condensed Matter and Materials Physics

 

(This special issue is based on the papers presented at 2nd National Conference on Condensed Matter and Materials

Physics at Department of physics, University of Rajasthan, Jaipur during February 1-3, 2007)

 

 

CONTENTS

Foreword

365

Z H Zaidi

 

Preface

367

N S Saxena & Kananbala Sharma

 

Papers

 

Thermodynamic properties of magnetic liquid metals in undercooled region

371

Heena Dhurandhar, T Lilly, Shanker Rao, Kirit N Lad & Arun Pratap*

 

Electronic and structural properties of transition metal mono nitrides

375

Poonam Ojha, Bipul Rakshit, G Pagare & Sankar P Sanyal*

 

Empirical high pressure equation of state for nano materials

378

Manoj Kumar & M Kumar

 

Study of electron paramagnetic resonance in vanadyl doped tungsten lithium borate glasses

382

Anshu*, S Rani, A Agarwal, S Sanghi, N Kishore & V P Seth

 

Measurement of thermal properties of polyaniline salt from room temperature 30 to 140 ºC

385

Neeraj Jain, Dinesh Patidar, N S Saxena* & Y K Saraswat

 

Kinetic analysis of crystallization processes in amorphous 2826A (Ni36Fe32Cr14P12B6) metallic glass

390

T Lilly Shanker Rao, Heena D Dhurandhar , Kirit N Lad & Arun Pratap*

 

Electronic transport property of liquid Cd-Te alloys

394

Manjul Kumar, P N Gajjar*, B Y Thakore & A R Jani

 

First principles study of pressure induced magnetic transition in CrO2

397

Vipul Srivastava, Sankar P Sanyal* & M Rajagopalan

 

Effect of swift heavy ion irradiation on the optical properties of sapphire

400

K S Jheeta, D C Jain, Ravi Kumar* & K B Garg

 

Theory for transport properties of non-spherical molecules of molecular fluids

403

Tarun Kumar Dey

 

Temperature dependence of thermal expansivity and volume thermal expansion of fullerene

406

A K Srivastava & B R K Gupta*

 

High pressure structural phase transition of three diluted magnetic semiconducting compounds

410

Gitanjali Pagare & Sankar P Sanyal*

 

Structural and thermal characterization of metal halides doped polypyrrole

414

Rashmi Saxena, Vinodini Shaktawat, Neeraj Jain, N S Saxena*, Kananbala Sharma & T P Sharma

 

Structural phase transition of AgI under high pressure

417

Deoshree Baghmar, Purvee Bhardwaj, D C Gupta* & N K Gaur

 

Superconductivity in Mg1-xMxB2 (M = Cu and Ag) system

420

Kiran Singh*, Rajneesh Mohan, Vilas Shelke, N K Gaur & R K Singh

 

Mössbauer study on the effect of nanosized titanium substitution in Mn Zn ferrite

423

V Anup Kumar & N Vasudevan Nair*

 

Temperature dependence of conductivity of polypyrrole doped with sulphuric acid

427

Vinodini Shaktawat, Neeraj Jain, Manasvi Dixit, N S Saxena*, Kananbala Sharma & T P Sharma

 

Bulk modulus of some simple liquid metals

431

P B Thakor, V N Patel, B Y Thakore, P N Gajjar & A R Jani*

 

Copper phthalocyanine films for photovoltaic applications

435

Himani Gupta, Aman Mahajan & R K Bedi*

 

Dielectric properties and surface morphology of proton irradiated ferric oxalate dispersed PVC films

439

Sejal Shah, Dolly Singh, Anjum Qureshi, N L Singh*, K P Singh & V Shrinet

 

High-pressure study of Na: A mean-field potential approach

443

N K Bhatt, P R Vyas, V B Gohel & A R Jani*

 

Specific heat studies of hexagonal manganites RMnO3 (Y, Sc, Lu) at low temperature

447

Nupinderjeet Kaur, Rajneesh Mohan, N K Gaur*& R K Singh

 

Low temperature properties of La2/3Ba1/3MnO3 perovskite manganite

451

N K Gaur* & Archana Srivastava

 

 

 

__________

*The corresponding author has been indicated by (*) mark in case of papers with more than one author.

 

 

 

 

 

 

 

Foreword

 

In the past decade, the field of condensed matter and materials physics (CMMP) has enlarged its scope enormously, embracing a far wider range of problems than ever before. At the heart of CMMP has been the quest to understand through a combination of experimental, theoretical and computational investigation, how unexpected phenomena emerge when large number of constituents interact with each other. This tremendous range of constituents leads to a spectacular diversity of emergent phenomena. By understanding these phenomena, CMMP researchers affect people’s lives in the countless ways from improving our understanding of nature to developing new technologies. The advances, as a result of discoveries in CMMP, have brought us to integrated circuits, magnetic resonance imaging(MRI), low loss optical filters, solid state lasers, light emitting diodes, magnetic recording discs and high performance composite materials and many more. Nanotechnology is the most popular subfield of CMMP due to its potential to revolutionalize science and technology. It is heartening to note the upsurge in India also in this novel field.

The 2nd National Conference on Condensed Matter and Materials Physics held at the Department of Physics, University of Rajasthan, Jaipur during February 1-3, 2007 has provided an excellent opportunity to researchers from all over the country to uncover what is at the heart of CMMP in the form of invited talks and contributed papers. The publication of special issue on Condensed Matter and Materials Physics in Indian Journal of Pure and Applied Physics has provided the contributing participants a befitting and vital record of the proceedings. The tireless efforts of Prof N S Saxena, Chairman, CMMP-07, Dr (Mrs) Kananbala Sharma, Convener of CMMP-07 and
Mrs. Poonam Bhatt, Editor, IJPAP deserve a special applaud to host the conference most successfully and to bring out the special issue.

 

                                                                                                                                Prof Z H Zaidi

                                                                                                                     Former Vice-Chancellor

                                                                                                            M J P Rohilkhand University

                                                                                                                                            Bareilly

        

    


Preface

 

Condensed Matter and Materials Physics is the subfield of Physics that has the largest number of direct practical applications. Most materials are made of simple, well understood constituents and yet their aggregate behaviour is stunningly diverse and often deeply mysterious. The innate urge to uncover the technological advances in the thriving areas was the driving force in organizing the 2nd National Conference on Condensed Matter and Materials Physics at Department of Physics, University of Rajasthan, Jaipur during February 1-3, 2007.

The Conference was inaugurated on February 1, 2007 in the Humanities Hall of the University by Prof Z H Zaidi, Former Vice-Chancellor, Rohilkhand University, Bareilly. He is an eminent Physicist working at Jamia Millia Islamia. The Presidential address was delivered by Dr N K Jain, Vice-Chancellor, University of Rajasthan, Jaipur.

This inaugural session was followed by the scientific sessions categorized broadly as:

1.      Mesoscopic Physics and Nanomaterials

2.      Semiconducting  and Superconducting Materials

3.      Biological Physics and Soft Matter

4.      Correlated Electron Systems

5.      Materials at High Pressure and Temperature

6.      Geophysically Important Materials

7.      Magnetic Materials

8.      Statistical Mechanics

9.      Glasses and Conducting Polymers

The Conference was well attended by about 150 participants from across the country. Within the short period of 3 days there were 13 Invited Talks, 28 Oral Presentations and 52 Poster Presentations on nanomaterials, multi-walled carbon nanotubes, production of nanocrystalline silicon and the study of materials at high temperature and pressure, novel ceramics, superconductors, polymers and their properties, optical, thermal and electrical properties of semiconducting materials etc.

The delegates thoroughly enjoyed the excellent exposure to emergent fields included in the invited talks.

In order to boost the quality of presentations and interest in young researchers in the novel areas of research, it was decided to give awards as a recognition of excellence in oral as well as poster presentations. The participation of the younger minds from amongst the M.Sc. students was exemplary and their keeness to gather the best output justified their constant presence in all the sessions.We hope that this conference has provided the appropriate forum to all the delegates for continuing academic relationship and enriching experiences.

It is a matter of profound privilege for us to thank all the members of the national advisory committee, the invited speakers and the local organizing committee for their guidance, participation and support. We also put on record our special gratitude to Dr N K Jain, Vice-Chancellor, University of Rajasthan, Jaipur,  for his constant guidance and unstinted support to the conference. The event would not have been made possible without the support of our sponsors DST, UGC, DRDO, AICTE, CSIR and BRNS, all of whom we gratefully acknowledge. We also express our sincere gratitude to institutions at Jaipur who always come forward in nurturing academics and have supported this conference. In this regard, we must thank Jaganath Gupta Institute of Technology (JNIT), Jaipur Engineering College (JEC, Kukas), Stani Memorial College for funding and International College of Girls (ICG), Poornima College of Engineering (PCE) for providing infrastructure support.

Last but not the least we wish to thank all the delegates who travelled from far and wide and made the conference a grand success. A special word of thanks to Prof. B K Srivastava, Head, Department of Physics, University of Rajasthan, Jaipur for his cooperation throughout the event. Finally, we thank Mrs Poonam Bhatt and Mrs Prabha Gupta for their support in bringing out this special issue of Condensed Matter and Materials Physics after the papers were thoroughly peer reviewed. 

 

Guest Editors

        Prof N S Saxena and Dr Kananbala Sharma

                                                                                                                     Department of Physics,
                                                                                                           University of Rajasthan, Jaipur


 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 371-374

 

Thermodynamic properties of magnetic liquid metals in undercooled region

Heena Dhurandhar1, T Lilly Shanker Rao1,2, Kirit N Lad1 & Arun Pratap1

1Condensed Matter Physics Laboratory, Applied Physics Department, Faculty of Technology & Engineering,

M S University of Baroda, Vadodara 390 001

2Electronics Department, Narmada College of Science & Commerce, Zadeshwar, Bharuch 392 011

Received 28 October 2007; revised 11 March 2008; accepted 2 April 2008

The experimental study of the thermodynamic properties of liquid metals has been confined usually to the stable liquid range of temperature and pressure. Nevertheless, there is a significant range between the melting point and the glass transition over which the liquid state can exist in a metastable equilibrium provided that crystallization can be avoided. The specific heat of undercooled liquid metals is a very important thermodynamic parameter. Appropriate knowledge of DCpl-x i.e. the difference of specific heats of undercooled liquid and the corresponding crystalline solid can be utilized to derive accurate results for the parameters like DG, DS and DH. However, the experimental determination of Cp in undercooled system is difficult due to its metastable nature. Still, it is possible to arrive at an expression for the DCpl-x, if the value of DCpm i.e. specific heat difference at melting point and the nature of variation of DCpl-x in undercooled region can be estimated. In the present paper, DG for pure liquid Co and Ni have been estimated using linear temperature dependence of DCp in the undercooled region. Further, a general expression has been used which is valid in a large temperature range. The calculated results for DG are in excellent agreement with experimental data. Other thermodynamic parameters like DS and DH are also evaluated.

Keywords: Liquid metals, Thermodynamic properties

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 375-377

 

 

Electronic and structural properties of transition metal mono nitrides

Poonam Ojha1,*, Bipul Rakshit1, G Pagare2 & Sankar P Sanyal1

1Department of Physics, Barkatullah University, Bhopal 462 026

2Government M L B Girls P G College, Bhopal

*E-mail: pooja_50123@rediffmail.com

Received 28 October 2007; revised 8 March 2008; accepted 7 April 2008

The electronic and elastic properties of rock-salt structured nitrides, namely TiN and VN have been studied using ab-initio pseudopotential scheme and local density approximation. Both the compounds show metallic behaviour, with a large gap between occupied and unoccupied states. The mechanical and the elastic properties show excellent agreement with experimental results and well compared with other theoretical results because of the inclusion of partial core correction in the present calculation.

Keywords: ab- initio calculations, Atoms electronic structural calculation, Electronic properties, Structural

 

 

  Indian Journal of Pure & Applied Physics

  Vol. 46, June 2008, pp. 378-381

 

    

          Empirical high pressure equation of state for nano materials

 

Manoj Kumar & M Kumar

Department of Physics, G B Pant University of Agriculture and Technology, Pantnagar 263 145

E-mail: munish_dixit@yahoo.com

Received 28 October 2007; revised 18 March 2008; accepted 31 March 2008

An empirical high pressure equation of state is obtained by modifying the Shanker formulation, widely used in the literature to study the thermal properties of solids. The relation is used to study the compression behaviour of carbon nanotubes (bundle and individual tube). The results obtained are compared with the available experimental data. It is found that the relation obtained in the present work gives the results which are in the better agreement with the experimental data as compared with the earlier relation. The results are reported for bundle as well as for individual carbon nanotube.

Keywords: High pressure, Compression, Carbon nanotubes

  Indian Journal of Pure & Applied Physics

  Vol. 46, June 2008, pp. 382-384

 

 

  Study of electron paramagnetic resonance in vanadyl doped tungsten lithium borate glasses

Anshu*, S Rani, A Agarwal, S Sanghi, N Kishore & V P Seth

Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125 001

*E-mail: ans_gju@yahoo.com

Received 28 October 2007; accepted 7 April 2008

Glasses with composition xWO3.(30-x)Li2O.70B2O3 containing 2 mol % V2O5 have been prepared over the range 0≤ x≤ 15 (x is in mol % and in steps of 2.5). The electron paramagnetic resonance (EPR) spectra of VO2+ in these glasses have been recorded on X-band (v ≈ 9.14 GHz) at room temperature (RT). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter, P and Fermi contact interaction parameter, K, have been calculated. It has been found that V4+ ions in these glasses exist as VO2+ in octahedral coordination with a tetragonal distortion. Results suggest that the tetragonality of the V4+O6 complex changes with change in WO3:Li2O ratio. Values of theoretical optical basicity have also been calculated.

            Keywords: Glasses, Borate glasses, Electron paramagnetic resonance, Vanadyl ion

 

  Indian Journal of Pure & Applied Physics

  Vol. 46, June 2008, pp. 385-390

 

 

Measurement of thermal properties of polyaniline salt
from room temperature 30 to 140°C

 

Neeraj Jain1,2,  Dinesh Patidar1, N S Saxena1,* & Y K Saraswat3

1Semiconductor and Polymer Science Laboratory, Department of Physics, University of Rajasthan, Jaipur 302 004

2Department of Physics, Poornima College of Engineering, Sitapura, Jaipur 302 022

3Department of Chemistry, S.V College, Aligarh

                                       Received 28 October 2007; accepted 7 April 2008

 

The thermal transport properties of polyaniline (doped with HCl) have been measured using transient plane source (TPS) technique. Cl- doping is confirmed by FTIR spectroscopy. In the temperature range from room temperature 30 to 140ºC both effective thermal conductivity (λe) and effective thermal diffusivity (ke) increase with increase in temperature from 30 to 60ºC and become almost constant in the temperature range 60 - 100ºC. For further increase in temperature, the values of  λe and ke decrease. This behaviour of thermal transport properties in the above mentioned ranges of temperature is due to decrease in moisture content and conversion of single-phase crystalline structure into multiphase crystalline structures, respectively. It has also been found that the values of thermal transport properties are much higher for salt as compared to its base form. This is suggestive of the fact that a change of -NH- group of base form into –[[N+H] Cl-]- group in salt form takes place by doping of chloride ions.

           Keywords: Conducting polymers, Transient plane source, Effective thermal conductivity, Effective thermal  diffusivity

 

 

  

  Indian Journal of Pure & Applied Physics

  Vol. 46, June 2008, pp. 390-393

 

    Kinetic analysis of crystallization processes in amorphous 2826A
(Ni36Fe32Cr14P12 B6) metallic glass

T Lilly Shanker Rao1,2, Heena D Dhurandhar1 , Kirit N Lad1 & Arun Pratap1

1Condensed Matter Physics Laboratory, Applied Physics Department, Faculty of Technology and Engineering,
M S University of Baroda, Vadodara 390 001

2Electronics Department, Narmada College of Science and Commerce, Zadeshwar, Bharuch 392 011

*E-mail:apratapmsu@yahoo.com

               Received 28 October 2007 ; revised 11 March 2008 ; accepted 2 April 2008

 

The crystallization processes of 2826A (Ni36Fe32Cr14P12B6) metallic glass were investigated using differential scanning calorimetry (DSC) at various heating rates. The thermograms at all scanning rates show two exothermic events. Different methods of kinetic analysis were employed at non-isothermal condition to derive important kinetic parameters namely activation energy of crystallization (E), frequency factor (A) and Avrami exponent (n) for the two exothermic peaks. The obtained values of E for peaks 1 and 2 are 298 and 457 (kJ/mol), respectively. The obtained Avrami exponent values 2.2(peak1) and 1.6(peak2) indicate one-dimensional and surface crystallization, respectively.

           Keywords: Activation energy of crystallization, Frequency factor, Avrami exponent   

 

 

  Indian Journal of Pure & Applied Physics

  Vol. 46, June 2008, pp. 394-396

       

                             Electronic transport property of liquid Cd-Te alloys

Manjul Kumar, P N Gajjar*, B Y Thakore & A R Jani

Department of Physics, Sardar Patel University, Vallabh Vidyanagar 388 120

*Department of Physics, School of Sciences, Gujarat University, Ahmedabad 380 009

E-mail: manjulkumar@yahoo.com

                                  Received 28 October 2007; revised 22 February 2008; accepted 4 April 2008

 

The temperature dependent electrical resistivity of liquid Cd0.6Te0.4 alloys has been studied theoretically by employing Faber-Ziman formula. Also, the Faber-Ziman formulation is used to generate the partial structure factor of the liquid Cd0.6Te0.4 alloys at 1062oC. The electron-ion interaction is incorporated through a newly proposed local model potential alongwith Ichimaru-Utsumi (IU) dielectric screening function. Good agreement is achieved between the presently calculated results of resistivity with the experimental findings. Resistivity of liquid Cd0.6Te0.4 shows a semiconducting behaviour in the liquid phase. Thus, the resistivity data for Cd-Te system are in qualitative agreement with the nearly-free electron picture.

           Keywords: Semiconductors, Liquid alloys, Electronic transport properties, Liquid structures, Pseudopotential

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 397-399

       

          First principles study of pressure induced magnetic transition in CrO2

 

  

Vipul Srivastava, Sankar P Sanyal1 & M Rajagopalan2

1Department of Physics, Barkatullah University, Bhopal 462 026

2Department of Physics, Anna University, Chennai 600 025

§E-mail: vips73@yahoo.com

                                Received 28 October  2007; revised 5 March 2008; accepted 7 April 2008

 

Using first principles density functional theory calculations based on the tight-binding linear muffin tin orbital method, the magnetic and electronic structures for the ferromagnetic state of CrO2 at high pressure have been investigated. A pressure-induced second order magnetic phase transition from ferromagnetic (FM) to non-magnetic (NM) at very high pressure of 65 GPa is predicted. The ground state properties like magnetic moment and lattice parameter are in good agreement with the experimental results. The band structure and density of states are plotted for FM and NM states. In NM calculation at ambient conditions CrO2 shows metallic phase, while it shows half-metallic phase in FM state.

         Keywords: Transition metal compounds, Magnetic phase transition, Pressure effect, Electronic structure

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 400-402

 

 

  Effect of swift heavy ion irradiation on the optical properties of sapphire

K S Jheeta, D C Jain, Ravi Kumar* & K B Garg

Department of Physics, University of Rajasthan, Jaipur 302 004

Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067

                          Received 28 October 2007; revised 12 March 2008; accepted 4 April 2008

 

Single crystals of sapphire (Al2O3; Fe, Ti, Cr) were irradiated with 100 MeV Ti and 100 MeV Ni swift heavy ions (SHI) at fluence 1 ´1012, 5´1012 and 1´1013 ions/cm2. Photoluminescence (PL) spectra of pristine and irradiated sapphires were recorded at room temperature under 2.8 eV blue excitation. A broad band consisting of two emission bands centered at 2.48 and 2.30 eV corresponding to F2 and F22+ defect centers, respectively, were observed. The concentration of these centers increases monotonically with the Ti ions fluence. While in Ni irradiated sapphires, it increases up to 5´1012 ions/cm2 and then showed a decreasing trend at fluence 1х1013 ions/cm2. The changes in concentration of these defect centers are explained in term of creation of new defect centers (oxygen vacancies), cluster formation and quenching of these defect centers and are correlated with the nature of ions.

           Keywords: Swift heavy ions; Photoluminescence; Defect centers

 

 Indian Journal of Pure & Applied Physics

 Vol. 46, June 2008, pp. 403-405

 

    Theory for transport properties of non-spherical molecules of molecular fluids

 

Tarun Kumar Dey

Postgraduate Department of Physics, L S College, B R A Bihar University, Muzaffarpur 842 001

E-mail: tkdeyphy@gmail.com

                                Received 28 October 2007; revised 3 March 2008; accepted 12 April 2008

The transport properties of molecular fluids of non-spherical molecules via the Gaussian overlap potential with constant energy have been studied using perturbation method with a non-spherical reference system. Using Verlet-weis method, the effective diameter and radial distribution function have been derived. The theory is applied to calculate the transport properties such as shear viscosity and thermal conductivity of benzene. In all these cases, the agreement is found to be fairly good.

         Keywords: Molecular fluid, Transport properties, Non-spherical molecules

 

 

Indian Journal of Pure & Applied Physics

 Vol. 46, June 2008, pp. 406-409

 

  

Temperature dependence of thermal expansivity and volume thermal
expansion of fullerene

 

A K Srivastava

Department of Physics, Lovely Professional University, Phagwara 144 401

E-mail: srivastava_phy@yahoo co in

and

B R K Gupta

Department of Physics, G.B.Pant University of Agriculture and Technology, Pantnagar 263 145 (Uttaranchal)

                   Received 28 October 2007; revised 12 February 2008; accepted 2 April 2008

 

 

In recent years, there has been intense activity, both experimental and theoretical, in exploring fascinating physical properties of newer form of carbon, namely fullerenes. Fullerenes are currently being widely investigated since they show the anomalous properties of bulk modulus and specific heat of the materials as compared to the bulk material. A simple theoretical Equation of State model is used to analyze the temperature dependence of thermal expansion coefficient, relative volume change and isothermal bulk modulus of a fullerene C60. A good agreement between our theoretically calculated results and available experimental data has been obtained.

        Keywords: Nanomaterials, Thermal expansion, Fullerene

 

Indian Journal of Pure & Applied Physics

 Vol. 46, June 2008, pp. 410-413

 

 

  High pressure structural phase transition of three diluted magnetic
semiconducting compounds

 

Gitanjali Pagare1,2,* & Sankar P Sanyal2,*

1Government M L B Girls P G College, Bhopal, India

2Condensed Matter Physics Laboratory, Department of Physics, Barkatullah University, Bhopal, India

*E-mail: gita_pagare@yahoo.co.in, spsanyal@sancharnet.in

                                 Received 28 October 2007; revised 7 March 2008; accepted 7 April 2008

 

The high-pressure structural properties of three diluted magnetic semiconductor (DMS) compounds, viz Zn1-xMxSe (M=Cd, Fe and Mn) have been studied theoretically. The value of M-mole fraction x is given 0.16% for Fe, 0.1% for Cd and 0.24% for Mn. In order to investigate the high-pressure properties of these compounds, the two body potential approach has been used, which includes Coulomb term, short range repulsion and van der Waal interactions. It has been established that the potential used predict correctly the stability of zinc blende structure (ZBS) at ambient pressure. A good agreement between the experiment and the theoretical results has been achieved. The lattice parameter of all DMS ternary alloys obeys Vegards law very closely showing the linear dependence of lattice parameter on impurity composition. The 11.8, 9.3 and 9.2 GPa as phase transition pressure and 17%, 18.8% and 19% as percentage volume collapse for ZnFeSe, ZnMnSe and ZnCdSe alloys respectively, have been reported. This shows that these compounds get largely compressed during phase transition, though the % volume collapse overestimates the measured values. It has also been observed that the values of phase transition pressure for these alloys are less than their parent compound ZnSe (Pt= 14.4 GPa)

        Keywords: Ternary, Phase transition, Coulomb, Short range, Zinc blende

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 414-416

 

 

Structural and thermal characterization of metal halides doped    polypyrrole

Rashmi Saxena*, Vinodini Shaktawat, Neeraj Jain, N S Saxena**, Kananbala Sharma & T P Sharma

Semi-conductor and Polymer Science Laboratory, 5-6, Vigyan Bhawan, University of Rajasthan, Jaipur 302 004

*E-mail: n_s_Saxena@rediffmail.com, rashmi_saxena29@yahoo.co.in

                                  Received 28 October 2007; accepted 7 April 2008

 

Polypyrrole and its metal halide composites have been synthesized by chemical oxidation polymerization technique with ammonium peroxisulphate (oxidant) in aqueous hydrochloric acid medium. structural characterization of polypyrrole samples S1 (100% Co), S2 (25%Ni -75%Co), S3 (50%Ni -50%Co), S4 (75%Ni - 25%Co) and S5 (100%Ni) has been made by XRD and FTIR spectroscopy. Thermal transport properties such as effective thermal conductivity (λe) and effective thermal diffusivity (χe) of these samples have been measured simultaneously at room temperature and normal pressure using transient plane source (TPS) technique. The values of effective thermal conductivity and effective thermal diffusivity are found higher in all the above-mentioned samples except sample S3 (50%Ni-50%Co). This result can be explained on the basis of bonding of cobalt and nickel with polypyrrole matrix during their polymerization.

        Keywords: Effective thermal conductivity, Effective thermal diffusivity, Metal halide

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 417-419

 

 

  Structural phase transition of AgI under high pressure

Deoshree Baghmar, Purvee Bhardwaj, D C Gupta* & N K Gaur

Department of Physics, Barkatullah University, Bhopal 462 026

*School of Studies in Physics, Jiwaji University, Gwalior 474 011

E-mail: deoshreebaghmar@gmail.com

                                   Received 28 October 2007; revised 26 February 2008; accepted 4 April 2008

 

The effect of high pressure over the structural stability of silver iodide (AgI) has been investigated. The structural properties of silver iodide have been calculated using Two Body Potential Model, comprising of Long-Range (L-R) Coulomb and van der Waals interactions and Short-Range (S-R) Hafemeister Flygare (HF) type overlap repulsive interactions. The phase transition pressure (Pt) and relative volume collapse ∆[V(Pt)/V(O)] as a function of pressure calculated by us for  zinc-blende (B3) and tetragonal (BT) structure are found to be in good agreement with the available experimental data.

        Keywords: Gibbs free energy, Phase transition, Relative volume Collapse, High pressure


Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 420-422 

Superconductivity in Mg1-xMxB2 (M = Cu and Ag) system

Kiran Singha,*, Rajneesh Mohana, Vilas Shelkea, N K Gaura & R K Singhb

aSuperconductivity Research Lab, Department of Physics, Barkatullah University, Bhopal 462 026

bInstitute of Professional Scientific Studies and Research, Chaudhary Devilal University, Sirsa 125 055

                                            *E-mail: kiranpatyal@rediffmail.com

                        Received 28 October 2007; revised 5 March 2008; accepted 7 April 2008

 

The polycrystalline samples with nominal compositions Mg1-xMxB2 (M = Cu, Ag; x = 0, 0.05) have been synthesized through solid-state reaction method. All the samples were synthesized from the stoichiometric mixtures of Mg, B, Cu and Ag. The samples were sintered at 850°C for 2 h in the presence of high purity argon flow. The X-ray diffraction (XRD),
R-T measurement and scanning electron microscopy (SEM) techniques have been used for the characterization of samples for phase formation, superconducting transition temperature (Tc) and microstructure, respectively. It is noticed from the XRD patterns that the Cu and Ag doping leads to the formation of Mg-Cu and Mg-Ag alloys as the secondary phase, respectively along with the major phase of MgB2. In case of Cu doping Tc decreases slightly and Ag doping has no effect on it. The grain size remains the same with these dopings, but the grain connectivity improves.

         Keywords: Superconductivity, Doping, Critical temperature

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 423-426 

  Mössbauer study on the effect of nano-sized titanium substitution in Mn Zn ferrite

V Anup Kumar & N Vasudevan Nair

Department of Physics, M G College, Thiruvananthapuram, Kerala 695 004

E-mail: anupaparna@yahoo.co.in

                            Received 28 October 2007; revised 14 March 2008; accepted 3 April 2008

 

Manganese zinc ferrites with nano-sized titanium of composition Mn0.8Zn0.2TixFe (2-x)O4 for x = 0 to 0.2 were synthesized by solid state reaction method. Nanosized titanium was prepared by tartarate gel method. Mössbauer spectra of these samples were taken at room temperature using Co57 source. From the Mössbauer spectra, the internal magnetic field, isomer shift, quadrupole splitting, recoilless fraction and the Debye temperature of these samples were calculated for the iron nucleus at the two non-equivalent sites. It is observed that addition of titanium decreases the internal magnetic field and also produces changes in the isomer shift of both the sites. The electric quadrupole splitting and recoilless fraction decrease with the increase in titanium concentration. These observed phenomena are interpreted on the basis of super exchange interaction and the reaction between Fe2+ and Ti4+.

         Keywords: Mössbauer study, nano-sized titanium, Mn Zn ferrite

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 427-430

 

   

Temperature dependence of conductivity of polypyrrole doped with 

sulphuric acid

Vinodini Shaktawat, Neeraj Jain, Manasvi Dixit, N S Saxena, Kananbala Sharma & T P Sharma

Semiconductor and Polymer Science Laboratory, Department of Physics, University of Rajasthan, Jaipur 302 004

E-mail: n_s_saxena@rediffmail.com

                                    Received 28 October 2007; accepted 7 April 2008

 

Polypyrrole samples doped with sulfuric acid have been synthesized by using chemical oxidative polymerisation technique in different ways. The monomer mixed with acid (sample S1) and oxidant mixed with acid (sample S2) is characterized by XRD and FTIR spectroscopy. Electrical conduction in these doped samples are studied through the I-V measurements at room temperature as well as function of temperature from 313 to 473 K. The I-V lharacteristics for both the samples have been found to be linear but conductivity of sample S2 is found to be  higher. Temperature dependence of conductivity suggests a transition from semiconducting nature to metallic nature with increase in temperature. Activation energies for both the samples have been found to be in milli electron volt range, 96.76 meV and 116.72 meV for samples S1 and S2, respectively.

           Keywords: Conducting polymer, Electrical conduction, Temperature dependence, Activation energies

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 431-434

 

   Bulk modulus of some simple liquid metals

P B Thakor1, V N Patel2, B Y Thakore, P N Gajjar3 & A R Jani

1Department of Physics, Veer Narmad South Gujarat University, Udhna Magdalla Road, Surat 395 007

2Natubhai V. Patel College of Pure & Applied Sciences, Vallabh Vidyanagar 388 120

3Department of Physics, School of Sciences, Gujarat University, Ahmedabad 380 009

Department of Physics, Sardar Patel University, Vallabh Vidyanagar 388 120

E-mail: pbthakor@rediffmail.com

                     Received 28 October 2007; revised 29 February 2008; accepted 28 March 2008

 

The Bulk modulus BT of some simple liquid metals viz: Li, Na, K, Rb, Cs, Mg, Zn, Cd, Al, In, Tl and Pb have been  investigated on the basis of the long wavelength limit of the structure factor of one component plasma (OCP) reference system.  To describe the electron-ion interaction our well established model potential is used alongwith Sarkar et al. Mod Phys Lett, B12(1998) 639, dielectric function.  Good agreements between present results and experimental data have been achieved for monovalent liquid metals than the polyvalent liquid metals.  A comparison of present results with experiments establishes the success of present form of local pseudopotential and the OCP reference system in the investigation of the Bulk modulus BT of some simple liquid metals.

Keywords:  Pseudopotential, Bulk modulus, One Component Plasma reference

 


Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 435-438

 

Copper phthalocyanine films for photovoltaic applications

Himani Gupta1, Aman Mahajan2 & R K Bedi1,*

1Materials Science Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143 005

2 Postgraduate Department of Physics & Electronics, DAV College, Amritsar 143 001

*E-mail: srkbedi@rediffmail.com

                       Received 28 October 2007; accepted 10 April 2008

 

 

Hot wall technique has been used to grow a series of copper phthalocyanine (CuPc) films. These samples have been studied for their structural, optical and electrical properties. The X-ray diffraction and SEM pattern of these films show crystalline behaviour of films. The electrical conductivity and optical band gap of the films increase with increase in substrate temperature, whereas activation energy decreases. The activation energy of the films are found to lie in the range 0.45-0.55 eV. Analysis of optical absorption measurements on the films indicates that the interband transitions energies lie in the range 2.3-2.55 eV. Keeping in view, the electrical and optical properties of CuPc films single layer (fluorine doped tin oxide/CuPc/aluminium) and double layer (fluorine doped tin oxide/crystal violet/CuPc/aluminium) junctions have been fabricated under different experimental conditions. The J-V relationship for the single and double layer devices are found to be in good agreement with standard diode equation.

         Keywords: Evaporation, Copper phthalocyanine, Scanning electron microscopy, X-ray diffraction,
                                 Electrical properties , Optical properties, Photovoltaic devices

 

 

 

Indian Journal of Pure and Applied  Physics

Vol. 46, June 2008, pp. 439-442

 

  Dielectric properties and surface morphology of proton irradiated ferric oxalate dispersed PVC films

 

Sejal Shah1, Dolly Singh1, Anjum Qureshi1, N L Singh1*, K P Singh2 & V Shrinet3

1Department of Physics, M S University of Baroda, Vadodara 390 002

2Department of Physics, Punjab University, Chandigarh 160 014

3Electrical Research and Development Association, Vadodara 390 010

*E-mail: singhnl_msu@yahoo.com

                                  Received 28 October 2007; accepted 8 April 2008

 

Different concentrations of organometallic compound (ferric oxalate) have been dispersed in polyvinyl chloride (PVC) films. PVC has been synthesized by solution polymerization technique. These films have been irradiated with 3 MeV protons at a fluence of 1´1013 ions/cm2. The frequency response of dielectric behaviour has been studied both in pristine and irradiated samples using LCR meter in the frequency range100 Hz-10MHz. The results so obtained are explained using the universal law of dielectric behaviour (ε α f n-1). The results are also explained on the basis of intra-cluster motion. It is observed that the log conductivity increases with increase in metal concentration and also with the fluence. The dielectric constant/loss shows frequency dependent behaviour. SEM studies show that the particle size of metal compound decreases upon irradiation.

           Keywords: Proton irradiation, PVC, Organometallics, Dielectric properties, Universal power law, SEM

 

 

Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 443-446

 

   High-pressure study of Na: A mean-field potential approach

 

N K Bhatt*,1, P R Vyas1, V B Gohel1 & A R Jani2

1Department of Physics, Gujarat University, Ahmedabad 380 009

2Department of Physics, Sardar Patel University, Vallabh Vidyanagar, 388 120

*E-mail: bhattnisarg@hotmail.com

                                   Received 28 October 2007; accepted 10 April 2008

 

Study of anharmonicity through Grüneisen parameter is carried out for elemental Na at finite temperatures and pressures. The mean-field potential (MFP) approach has been employed in conjunction with the local pseudopotential to evaluate Helmholtz free energy at elevated temperatures and pressures. The calculated pressure and temperature variation of thermodynamic Grüneisen parameter (gth), pressure dependence of isothermal bulk modulus (BT) and total free energy at
T = 300-K have been calculated. Results obtained are satisfactorily compared with the experimental and other first principles data.

         Keywords: Helmholtz free energy, Grüneisen parameter, Bulk modulus, High-pressure

 

 Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 447-450

 

 

 Specific heat studies of hexagonal manganites RMnO3 (Y, Sc, Lu)
at low temperature

 

Nupinderjeet Kaur1, Rajneesh Mohan2, N K Gaur2 & R K Singh2,3

1Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016

2Department of Physics, Barkatullah University, Bhopal 462 026

3MATS University, MATS Tower, Pandri, Raipur 492 002

*Email: drnjkaur@rediffmail.com

                Received 28 October 2007; revised 26 March 2008; accepted 4 April 2008 The Rigid Ion Model (RIM) has been formulated by incorporating the effects of the long-range Coulomb attraction, the short-range Hafemeister-Flygare (HF) type overlap repulsion and van der Waals (vdW) interactions to investigate the temperature dependence of the specific heat of hexagonal manganites RMnO3 (R=Y, Sc, Lu) in the temperature range 10K £ T £ 100K. The comparison between our calculated and available experimental results on the specific heat (Cv) has shown an excellent agreement.

         Keywords: Hexagonal manganites, Specific heat, Thermal properties

 

 

 Indian Journal of Pure & Applied Physics

Vol. 46, June 2008, pp. 451-453

 

 

   Low temperature properties of La2/3Ba1/3MnO3 perovskite manganite

 

N K Gaur & Archana Srivastava

Department of Physics, Barkatullah University, Bhopal 462 026

Email: archanasaran@rediffmail.com

                       Received 28 October 2007; revised 7 March 2008; accepted 1 April 2008

 

The evolution of cohesive and thermal properties of La2/3Ba1/3MnO perovskite manganite was studied as a function of temperature (1K £ T £ 10K) by means of Rigid Ion Model (RIM). The heat capacity as a function of temperature computed from this model are, generally, in good agreement with their available experimental data measured with relaxation calorimetry technique. In addition, the results on the cohesive energy (f), molecular force constant (¦), Restrahalen frequency (no), Debye temperature (QD) and Gruneisen parameter (g) are also reported.

            Keywords: Specific heat, Thermodynamic properties, Debye temperature, Thermal properties, Manganites