Indian Journal of Pure and Applied Physics

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Volume 47

Number 2

FEBRUARY 2009

CODEN : IJOPAU 47 (2) 77-156

ISSN: 0019-5596

 

   

CONTENTS

Atomic and Molecular Physics

 

Infrared and magnetic study of nanophase zinc ferrite

81

Marykutty Thomas* & K C George

 

Electromagnetism, Optics, Acoustics, Heat transfer, Classical Mechanics and Fluid Dynamics

 

Ultrasonic investigation of amino acids in aqueous sodium acetate medium

87

S Thirumaran * & K Job Sabu

 

Determination of stability constants of charge transfer complexes of iodine monochloride and certain ethers in solution at 303K by ultrasonic method

97

V Kannappan, S J Askar Ali & P A Abdul Mahaboob

 

Physics of Gases, Plasmas and Electric Discharges

 

Resonant second harmonic generation in a plasma filled parallel plane waveguide

103

J Parashar

 

Condensed Matter: Structural, Mechanical and Thermal Properties

 

Pre-photoexcitation effects in 75MeV oxygen ion irradiated kapton-H polyimide

108

Anu Sharma & J K Quamara*

 

Structural and elastic properties of rare-earth nitrides at high pressure

114

Aditi Rukmangad, Mahendra Aynyas & Sankar P Sanyal*

 

Temperature dependence of microwave loss in antiferroelectric squaric acid crystal

119

Trilok Chandra Upadhyay

 

Grain boundary scattering in silicon doped polycrystalline gallium nitride films prepared by rf scattering

125

S R Bhattacharya & A K Pal*

 

Temperature dependence of microwave loss in rochelle salt crystal

134

Trilok Chandra Upadhyay* & Balkrishna Kandpal

 

Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties

 

Analysis of dielectric constants to determine sp3/sp2 ratio and effect of substrate bias on spectroscopic ellipsometric studies of tetrahedral amorphous carbon films grown using an S bend filtered cathodic vacuum arc process

141

O S Panwar *, Mohd Alim Khan, A Basu, Satyendra Kumar & Sushil Kumar

 

Interdisciplinary Physics and Related Areas of Science and Technology

 

Low-voltage variable current gain CCII based all-pass/notch filter

149

Susheel Sharma*, K Pal , S S Rajput, L K Mangotra & S S Jamuar

 

 

__________

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

 

 

 

 

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 81-86

 

 

Infrared and magnetic study of nanophase zinc ferrite

Marykutty Thomas1 & K C George2

1Department of Physics, B C M College Kottayam, Kerala 686 001

2Department of Physics, S B College Changanacherry, Kerala 686 101

 

Received 24 June 2008; revised 20 November 2008; accepted 22 December 2008

 

E-mail: marykutythomas@yahoo.co.in

 

Nanophase zinc ferrite (ZnFe2O4) has been prepared by co-precipitation under stoichiometric conditions. The effect of reactant concentration on particle size has been studied using XRD, structural details using IR absorption spectroscopy, thermal properties using TG/DTA analysis and magnetic moment using SQUID magnetometer measurement. IR spectroscopy has been found to be an important tool for characterizing nanophase ZnFe2O4 particles size in the range 4 to 28nm. The positions of the absorption band are found to be particle size dependent. The large increase in magnetization with decrease in particle size may be due to super exchange interaction between Fe3+ ions on two sublattices A and B. The morphology of the sample has been investigated by TEM and selected area electron diffraction pattern.

Keywords: Reactant concentration, Nanophase ZnFe2O4, IR spectroscopy, Magnetic moment, SQUID magnetometer

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 87-96

 

 

Ultrasonic investigation of amino acids in aqueous sodium acetate medium

S Thirumaran* & K Job Sabu

Department of Physics (DDE) Annamalai University, Annamalainagar 608 002

E-mail: thiru_phymaran@yahoo.co.in

Received 06 June 2008; revised 25 November 2008; accepted 30 December 2008

The ultrasonic velocity (U), density ( r) and viscosity (h) measurements have been carried out for four amino acids namely L-alanine, L-leucine, L-valine and L-proline in aqueous sodium acetate solution as a function of composition at 303, 308 and 313K. Experimental data have been used to estimate the adiabatic compressibility (b), change in adiabatic compressibility (Db), relative change in adiabatic compressibility (Db/b0), apparent molal compressibility (jK), apparent molal volume (jV), limiting apparent molal compressibility (), limiting apparent molal volume () and the constants (SK, SV) and viscosity B-Coefficient. The results are discussed in terms of structure-making or structure-breaking effects of amino acids in the mixture.

Keywords: Ultrasonic velocities, Amino acids, Aqueous sodium acetate, Adiabatic compressibility, Apparent molal compressibility, Apparent molal volume

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 97-102

 

 

Determination of stability constants of charge transfer complexes of iodine monochloride and certain ethers in solution at 303 K by ultrasonic method

 

V Kannappan*, S J Askar Ali & P A Abdul Mahaboob

Postgraduate and Research Department of Chemistry, Presidency College (Autonomous), Chennai 600 005

Received 13 July 2007; revised 13 August 2008; accepted 6 November 2008

Ultrasonic velocities (U), densities (ρ), and coefficient of viscosities (η) have been measured for solutions containing iodine monochloride (ICl) and one of the following ethers in the equimolar concentration in the range 0.001-0.01M at 303 K. Diphenyl ether, 4-chloroanisole, anisole and 1,4-dioxane are used as donors. Dichloromethane, chloroform, carbon tetrachloride and n-hexane have been used as solvents. Acoustical parameters such as adiabatic compressibility (β), absorption coefficient (α/f2), internal pressure (πi) and cohesive energy (CE) values are calculated from the measured values of U, ρ and η. The trend in the acoustical parameters establishes the formation of charge transfer complexes between iodine monochloride (acceptor) and ethers (donors). The stability constants (K) are calculated for these complexes. The free energy changes (ΔG) for the formation of these complexes are also calculated from K values. Attempt has been made to correlate the formation constants with polarizability, dielectric strength and dipole moment of the donor and solvent molecules. The free energy of activation (ΔG#) and viscous relaxation time (t) are found to be almost constant for these complexes indicating the formation of similar charge transfer complexes in these systems.

Keywords: Ultrasonic velocity, Formation constants, Donor-acceptor complexes, Iodine monochloride, Ethers

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 103-107

 

 

Resonant second harmonic generation in a plasma filled
parallel plane waveguide

 

J Parashar

Department of Applied Physics, Samrat Ashok Technological Institute, Vidisha (M P) 464 001

Received 24 April 2008; revised 8 August 2008; accepted 14 November 2008

A TE mode electromagnetic radiation propagating through plasma filled parallel plane guide in the presence of a density ripple, produces resonant second harmonic radiation in the TM mode. The ripple provides the phase matching. The required density ripple wave number increases with the plasma density. The amplitude of the ripple also needs to be non-uniform to produce net time average second harmonic power. The power conversion efficiency of harmonic scales is , the frequency of the pump.

Keywords : Laser plasma interaction, Second harmonic generation, Phase matching

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 108-113

 

 

Pre-photoexcitation effects in 75 MeV oxygen ion irradiated kapton-H polyimide

Anu Sharma & J K Quamara*

Department of Applied Physics, National Institute of Technology, Kurukshetra 136 119
E-mail: jkquamara@yahoo.com

Received 25 March 2008; accepted 23 December 2008

The pre-photoexcitation effect measured in the form of dark polarization (Id) under visible radiation in 75 MeV oxygen ion irradiated (Fluence: 1.81011, 3.11012 and 1.81013 ions/cm2) kapton-H polyimide has been investigated. The dependence of Id on exposure (ranging from 0 to 10000 W/m2) and the time interval Δt (ranging from 0 to 7 min) between the end of illumination and the outset of the polarizing electric field have been studied at operating temperatures of 80 and 200C under a biasing field of 240 kV/cm. The variation of Id with exposure shows a transitory saturation followed by a gradual descent. The band-band transition and the conversion of trapping sites into recombination centers have been held responsible for such behaviour. The ion irradiated samples, in general, show a decrease in Id as compared to pristine samples. The effect of fluence on Id is mainly associated with the enhancement of charge trapping density and the charge carrier mobility.

Keywords: Ion irradiation, Kapton-H, Pre-photoexcitation effects, Polymers

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 114-118

 

 

Structural and elastic properties of rare-earth nitrides at high pressure

Aditi Rukmangad, Mahendra Aynyas & Sankar P Sanyal*

Department of Physics, Sadhu Vaswani College, Bhopal 462 030

*Department of Physics, Barkatullah University, Bhopal 462 026

E-mail: aditi.rukmangad@yahoo.co.in

Received 25 March 2008; revised 19 December2008; accepted 2 January 2009

The structural and elastic properties of rare earth nitrides (REN) [RE=Tb, Ce] under high pressure have been investigated by using two body inter ionic potential theory with modified ionic charge (Zme) to include Coulomb screening effect. The present theoretical approach has predicted pressure-volume relationship curves which show that TbN and CeN exhibit a NaCl type structure at an ambient pressure and undergo a structural phase transition from NaCl into CsCl phase at 136 GPa and 88 GPa, respectively. The Second order elastic constants (SOECs), Third elastic constants (TOECs) and second order pressure derivatives for these compounds have also been reported. The variation of elastic constants (C11, C44) with pressure is also presented.

Keywords: High-pressure, Rare earth nitrides, Phase transition, Elastic constants

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 119-124

 

 

Temperature dependence of microwave loss in antiferroelectric
squaric acid crystal

 

Trilok Chandra Upadhyay

Physics Department, H N B Garhwal University, Srinagar (Garhwal), Uttarakhand 246 174

Received 1 April 2008; revised 22 July 2008; accepted 29 December 2008

A model of pseudospin for layers 1 and 2 of squaric acid (SQA) crystal proposed by Li and Qin, Ferroelectrics, 82 (1988), 69 has been modified to include pseudospin-phonon interaction and cubic and quartic phonon anharmonic interactions. With the help of double-time temperature dependent Green's function method and modified Hamiltonian, expressions for antiferroelectric soft mode frequency, dielectric constant and loss have been evaluated. By fitting model values of physical quantities in the theoretical expressions, temperature dependences of soft mode frequency and loss have been calculated. In the microwave frequency range, an increase in frequency is followed by increase in loss. The loss decreases with increase in temperature for SQA crystal in its paraelectric phase. This shows Curie-Weiss behaviour of the dielectric tangent loss. Theoretical results are compared with experimental results of Muser [Proc. 6th Int'l Meeting on Ferroelectricity, Kobe (1985)], Maier et al. [Phys Status Solidi (b) 89, (1978)], and Samara and Semmingsen [J Chem Phys 71 (3) (1979) 1401] which show a good agreement.

Keywords: Antiferroelectrics, Anharmonic interactions, Dielectric, Loss tangent

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 125-133

 

 

Grain boundary scattering in silicon doped polycrystalline gallium nitride films prepared by rf sputtering

S R Bhattacharyya & A K Pal*

Department of Instrumentation Science, USIC Building, Jadavpur University, Calcutta 700 032

*E-mail: msakp2002@yahoo.co.in

Received 15 October 2007; revised 25 November 2008; accepted 30 December 2008

Silicon doped polycrystalline gallium nitride films have been deposited at temperatures ranging from 300 to 623 K on fused silica and silicon substrates by radio frequency sputtering technique. The films are characterized by optical measurements while the microstructural information is obtained from scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy studies indicate compositional information in these films. The bonding environment in the film has been revealed from Fourier transformed infrared studies. Grain boundary parameters like density of trap states and barrier height are also evaluated.

Keywords: Group III nitrides, Grain boundary, X-ray photoelectron spectroscopy, FTIR

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 134-140

 

 

Temperature dependence of microwave loss in rochelle salt crystal

 

Trilok Chandra Upadhyay* & Balkrishna Kandpal

Physics Department, H N B Garhwal University,
Srinagar (Garhwal), Uttarakhand 246 174

*E-mail: trilokphys@yahoo.co.in

Received 13 December 2007; revised 8 July 2008; accepted 26 December 2008

Considering two-sublattice pseudospin lattice coupled mode model [Chaudhuri et al., J Phys Soc Jpn, 49(1980) 609] along with third-and fourth-order phonon anharmonic interaction terms and using double-time thermal Green's function method, expressions for shift, width, renormalized soft mode frequency, Curie temperature, dielectric constant and microwave absorption have been derived and discussed for rochelle salt crystal. By fitting model values of physical quantities, soft mode frequency, dielectric constant and microwave loss tangent have been calculated. Theoretical results compare well with experimental results of Sandy and Jones, Phys Rev, 168 (1968) 481.

Keywords: Microwave loss, Rochelle salt crystal, Pseudospin lattice coupled mode, Microwave absorption

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 141-148

 

 

Analysis of dielectric constants to determine sp3/sp2 ratio and effect of substrate bias on spectroscopic ellipsometric studies of tetrahedral amorphous carbon films grown using an S bend filtered cathodic vacuum arc process

O S Panwara, Mohd Alim Khana, A Basub, Satyendra Kumarc & Sushil Kumara

aPlasma Processed Materials Group, National Physical Laboratory, New Delhi 110 012

bDivision of Electronic Materials, National Physical Laboratory, New Delhi 110 012

cDepartment of Physics, Indian Institute of Technology, Kanpur 208 016

E-mail: ospanwar@mail.nplindia.ernet.in

Received 29 May 2008; revised 1 December 2008; accepted 15 December 2008

The carbon bonding ratio and optical properties have been studied by spectroscopic ellipsometry of as grown tetrahedral amorphous carbon (ta-C) films, deposited using an S bend filtered cathodic vacuum arc (FCVA) process. First, the carbon bonding ratio in ta-C films has been estimated from imaginary part of dielectric constant (e2) spectra obtained by spectroscopy ellipsometry. A method has been developed to find out the fractions of sp3and sp2 bonded carbon atoms from the Wemple-Didomenico plot. Second, the effect of varying negative substrate bias on the optical properties and sp3/sp2 ratio of as-grown ta-C films has been made. The values of the optical constants evaluated are found to increase with the increase of the negative substrate bias in the as-grown ta-C films but the values of sp3/sp2 ratio and the optical band gap (Eg) evaluated increase up to -200 V substrate bias and beyond -200 V substrate bias the values of sp3/sp2 ratio and Eg decrease. Application of substrate bias is, thus, found to increase the sp3 bonding and Eg up to -200V substrate bias and beyond -200V substrate bias there is reversal of the trend.

Keywords: Spectroscopic ellipsometry, Optical constants, FCVA, sp3/sp2, ta-C, Substrate bias

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, February 2009,pp 149-152

 

 

Low-voltage variable current gain CCII based all-pass/notch filter

Susheel Sharma1, K Pal2, S S Rajput3, L K Mangotra1 & S S Jamuar4

1Department of Physics and Electronics, University of Jammu, Jammu 180 006

2Department of Earthquake Engineering, Indian Institute of Technology, Roorkee

3ABV Indian Institute of Information Technology and Management, Gwalior

4Department of Electrical and Electronic Engineering, University Putra Malaysia, Malaysia

E-mail: susheelksharma@gmail.com

Received 12 August 2008; accepted 12 December 2008

A second order low-voltage current conveyor type II (CCII) based filter circuit which can realize dual filter functions (all-pass/notch) depending on the current gain of CCII has been presented. The circuit employs equal valued components with all capacitors grounded and is more suitable for chip implementation. The circuit offers high input impedance, low output impedance and employs same type of active devices (CCII+). Theoretical results have been validated by PSpice simulations using 0.5 m technology parameters at supply voltage of 0.75 V.

Keywords: Low-voltage circuits, Current conveyor, Active filter

 

 

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