Indian Journal of Pure and Applied Physics

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Volume 47

Number 4

APRIL 2009

CODEN: IJOPAU 47 (4) 237-320

ISSN: 0019-5596

 

   

     CONTENTS

Atomic and Molecular Physics

 

Spectroscopic and dc conductivity studies of Cu2+  spin probe in 10Li2O-xNb2O5-(89-x)
TeO2 glass system

241

J Chinna Babu & V Chandra Mouli*

 

Molecular  structure and vibrational spectra of 2-chlorobenzoic acid by density functional
theory and ab-initio Hartree-Fock calculations

248

N Sundaraganesan *, B Diminic Joshua & T Radjakoumar

 

Vibrational analysis of pyrazinamide

259

S Gunasekaran* & E Sailatha

 

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

 

Ultrasonic study of n-alkanols in toluene with nitrobenzene

265

S Thirumaran * & J Earnest Jayakumar

 

Condensed Matter: Structural, Mechanical and Thermal Properties

 

Thermal diffusivity of advanced composite materials of e-glass fiber reinforced plastic
in the temperature range 5-120K

273

Kalobaran Das , S M Kamaruzzaman, Tapas Ranjan Middya* & Siddhartha Datta

 

Effect of dopants on barium hexaferrite

277

S V Salvi* & V H Joshi

 

Preparation and characterization of ceramic samples of silver sodium niobate mixed system

282

Om Prakash Nautiyal, S C Bhatt*, R P Pant, A A Bourai, P K Singh, R Saxena & B S Semwal

 

Effect of structural parameters on variation of microstructural and magnetic properties of
nanocrystalline alloy of Fe73.5Cu1Nb3Si17.5B5

289

M M Uddin*, S Manjura Hoque, M Sultan Mahmud, M A Hakim & F U Z Chowdhury

 

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

 

Field dependent soft mode frequency in BaxSr1-xTiO3 ferroelectric perovskites

300

Ashok Kumar, Ashish Kukreti & U C Naithani*

 

Interdiscplinary Physics and Related Areas of Science and Technology

 

New low-voltage class AB current conveyor II for analog applications

306

Parshotam S Manhas*, K Pal, Susheel Sharma, L K Mangotra & K K S Jamwal

 

Performance of non-linear amplifier based PLL systems in presence of channel perturbations

310

B De & B C Sarkar*

 

__________

*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, April 2009, pp. 241-247

 

 

Spectroscopic and dc conductivity studies of Cu2+ spin probe

in 10Li2O- xNb2O5-(89-x)TeO2 glass system                                                                

J Chinna Babu & V Chandra Mouli

Glassy Materials Research Laboratory, Department of Physics, Osmania University, Hyderabad 500 007, Andhra Pradesh

E-mail: vorucm90@yahoo.com

Received 27 June 2008, revised 11 December 2008; accepted 2 February 2009

DSC, ESR, IR, Raman, optical absorption and dc conductivity studies on 10Li2O- xNb2O5-(89-x) TeO2 glasses containing Cu2+ spin probe have been carried out. Glass transition temperature (Tg) and thermal stability of glass samples are estimated from the DSC measurements and it has been found that both increase with increasing the Nb2O5 content. From IR and Raman spectra, it is clear that, the glass system consists of structural units of TeO3 (tp), TeO4 (tbp) and NbO6 octahedra. TeO4 units are found to be converted into TeO3 units with increase in Nb2O5 content. From ESR spectra, it is found that the Cu2+ ion is in tetragonal distorted octahedral site with as ground state. The observed optical absorption peak of Cu2+ is found to be maximum at 800 nm for 10 mol% of Nb2O5 content. Bonding parameters and per cent bonding symmetry are calculated from both optical and ESR data and are found to change with increase in Nb2O5 content. The observed dc conductivity is found to be increasing with temperature and decreasing with increase in Nb2O5 content.

Keywords: Infrared spectroscopy, Raman spectroscopy, ESR spectroscopy, dc Conductivity, Tellurite glasses

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 248-258

 

 

Molecular structure and vibrational spectra of 2-chlorobenzoic acid by density functional theory and ab-initio Hartree-Fock calculations

N Sundaraganesana, B Dominic Joshuab & T Radjakoumarc

aDepartment of Physics (Engg.), Annamalai University, Annamalai Nagar 608 002, India

bDepartment of Physics, IFET College of Engineering, IFET Nagar, Gangarampalayam, Villupuram 605 108, Tamil Nadu

cDepartment of Physics, KMCPG Studies, Lawspet, Puducherry 605 008

aE-mail: sundaraganesan_n2003@yahoo.co.in

Received 15 July 2008; revised 16 December 2008; accepted 3 February 2009

The structure, harmonic frequencies and vibrational mode assignments for 2-chlorobenzoic acid (2CBA) monomer are calculated using HF and DFT methods employing the 6-311++G(d,p) basis set. The results of the molecular structure and vibrational frequencies obtained on the basis of calculations are presented and critically compared with the experimental IR data recorded in gas phase. The Raman and IR spectral data of 2-chlorobenzoic acid (2CBA) obtained in solid phase have also been included. The normal mode analysis has been carried out for all the modes. Most of the modes have wavenumbers in the expected range. The experimental spectra also coincide satisfactorily with those of theoretically constructed spectrograms.

Keywords:  FTIR, FT-Raman spectra, ab-initio, DFT, 2-chlorobenzoic acid, Vibrational analysis

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 259-264

 

 

Vibrational analysis of pyrazinamide

S Gunasekaran & E Sailatha

Spectro Physics Research Laboratory, Pachaiyappa’s College, Chennai 600 030

Received 9 October 2007; accepted 26 December 2008

Pyrazinamide (PZA) is an antitubercular drug, with molecular formula C5H5N3O. The FTIR and FT Raman spectra of PZA have been recorded in the region 4000 - 400cm-1 and 3500 – 50cm-1 , respectively for molecular study. A detailed vibrational analysis has been made on the fundamental modes of vibration. A normal coordinate analysis has been carried out for PZA following the Wilson’s FG matrix method. A set of potential constants has been evaluated using the method of kinetic constants on the basis of C1 point group symmetry. The evaluated potential constants have been compared with those of related molecules and are in the expected range to confirm the correctness of the assignments made. To check whether the chosen set of vibrational frequencies contributes maximum to the potential energy associated with the normal coordinates of the molecule, potential energy distribution (PED) has been evaluated.

Keywords: Fourier transform infrared spectra, Fourier transform Raman spectra, Pyrazinamide, Vibrational band assignments, Normal coordinate analysis, Potential energy distribution

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 265-272

 

 

Ultrasonic study of n-alkanols in toluene with nitrobenzene

S Thirumaran* & J Earnest Jayakumar

*Department of Physics, D D E Annamalai University, Annamalainagar 608 002

E-mail: thiru_phymaran@yahoo.co.in

Received 21 April 2008; revised 29 December 2008; accepted 7 January 2009

The ultrasonic velocity, density and viscosity of the mixtures of the n–alkanols, namely, 1–propanol, 1–butanol, and 1–pentanol in toluene with nitrobenzene at 303 K have been measured. From the measured data of ultrasonic velocity, density and viscosity, some of the acoustical parameters such as adiabatic compressibility (b), free length (Lf), free volume (Vf) and internal pressure (pi) have been measured. The excess values of the above parameters are also evaluated. The results have been analysed and interpreted in terms of molecular interactions such as dipole-dipole interaction through hydrogen bonding between nitrobenzene and 1-alkanols, and donor-acceptor complexity observed between toluene and nitro-benzene molecules.

        Keywords: Adiabatic compressibility, Free length, Free volume, Internal pressure, Hydrogen-bonding, Dipole-dipole interactions

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 273-276

 

 

Thermal diffusivity of advanced composite materials of e-glass fiber reinforced plastic in the temperature range 5-120K

Kalobaran Das1, S M Kamaruzzaman1, Tapas Ranjan Middya1* & Siddhartha Datta2

1Department of Physics, 2Department of Chemical Engineering,

Jadavpur University, Kolkata 700 032

*E-mail: middya@phys.jdvu.ac.in

Received 22 September 2008; revised 11 December 2008; accepted 3 February 2009

Thermal diffusivity of plain-woven fabric composite in a closed cycle cryo-refrigerator (CCR) based setup in the temperature range 5-120K has been studied. The modified temperature wave method (Angstrom) is applied to measure the thermal diffusivity of glass fiber reinforced plastic (GFRP). The set up is a plug in type which can be used anywhere because of its portability and also works without use of any cryogenic fluid. The results show that there exists an inverse relation between the thermal diffusivity of e-glass fiber composite and temperature in very low temperature domain but decreases very slowly after 100K.

Keywords: Thermal diffusivity, Cryogenic temperature, Phase difference

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 277-281

 

 

Effect of dopants on barium hexaferrite

S V Salvi* & V H Joshi+

*Material Physics Lab, Department of Physics, Birla College, Kalyan, Mumbai, 421 304

+Department of Physics, Bhavans H S College, Chowpatty, Mumbai 400 007

E- mail: v_joshi1966@yahoo.com

Received 11 August 2008; revised 8 December 2008; accepted 16 February 2009

Samples of Ba1.266Ti2.956 Fe7.6Li0.844O19 hexaferrite have been prepared using anatase and rutile phases of TiO2 by classical ceramic route. A pure sample of Ba Fe12O19 has also been prepared for comparison. The structural, electrical and magnetic characteristics have been studied by XRD, SEM, FTIR, two probe method, hysteresis loop and susceptibility curves. The samples exhibit hexagonal magnetoplumbic structure with spacegroup P63/mmc and p type ferrimagnetic behaviour. BaFe12O19 is a hard ferrite, however, the substituted hexaferrites are soft ferrites. The substitution causes increase in grain size and particle size. The Mc value, coercive force Hc, squareness MR/Ms and Curie temperature Tc are large for rutile TiO2 based samples as compared to anatase TiO2 based samples. However, the anatase allotrope based samples enhance the grain growth. These materials can be used in the applications related to magnetic recording, microwave absorption and EM absorption.

Keywords: Polycrystalline ferrites, Hexaferrites, Curie temperature, Magnetoplumbic

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 282-288

 

 

           Preparation and characterization of ceramic samples of
silver sodium niobate mixed system

 

Om Prakash Nautiyal, S C Bhatt, R P Pant*, A A Bourai, P K Singh, R Saxena & B S Semwal

Department of Physics, H N B Garhwal University, Srinagar, Srinagar Garhwal, Uttarakhand 246 001

* National Physical Laboratory, New Delhi 110 012

E-mail: nautiyal_omprakash@yahoo.co.in

Received 6 May 2008; revised 1 February 2009; accepted 3 March 2009

Ceramic pellets of Ag1-xNaxNbO3 (x = 0, 0.3, 0.5 and 0.7), system have been prepared by solid-state reaction method and sintering process. The prepared samples are characterized by XRD and SEM techniques. Lattice parameters and crystallite size have been calculated by XRD pattern and grain size has been calculated by SEM. It has been observed that all the prepared samples show orthorhombic structure at room temperature.

Keywords: Dielectrics, Ceramics, X-ray diffraction, Scanning electron micrographs

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 289-299

 

 

Effect of structural parameters on variation of microstructural and magnetic properties of nanocrystalline alloy of Fe73.5Cu1Nb3Si17.5B5

M M Uddin1*, S Manjura Hoque2, M Sultan Mahmud3, M A Hakim2 & F U Z Chowdhury1

1Department of Physics, Chittagong University of Engineering & Technology (CUET), Chittagong-4349, Bangladesh

2Materials Science Division (MSD), Atomic Energy Centre, P.O. Box No: 164, Dhaka-1000, (AECD) Bangladesh

3Department of Physics, University of Asia Pacific, Dhaka-1209, Bangladesh

*E-mail: mohi@cuet.ac.bd

Received 13 July 2008; accepted 6 January 2009

Amorphous ribbons of Fe73.5Cu1Nb3Si17.5B5 alloy have been annealed in the temperature range 475-700°C for X-ray diffraction (XRD) patterns. Crystallization induced by heat treatment resulted in the formation of a Fe-Si phase. The phase formed by primary crystallization has been found to be Fe-Si solid solution with a composition corresponding to disordered Fe-Si. Secondary crystallization of the Fe3B and Fe2B phases arises with the individual branches at the interfaces of the closely spaced crystals at the temperature 680°C, the spacing of such crystals was of the order of nanometer. Samples have been annealed in a controlled way in the temperature range 510-700°C with an interval of 10°C to 30°C for 1 h in order to study the effect of structural parameters of the nanocrystalline Fe(Si) grains on the variation of microstructural and soft magnetic properties. Temperature and frequency dependence of initial permeability of amorphous and devitrified toroid shaped samples have been measured. The permeability values showed little change as annealing time. Enrichment of Curie temperature has been observed for amorphous alloy due to the irreversible structural relaxation. The microstructures of the annealed samples are characterized as solid solutions of bcc Fe(Si) crystallites with grain sizes 5-19 nm and an abrupt increase 53 nm at 700°C. Silicon contents in the nanocrystalline phases determined from the lattice parameters are 12.67 to 15.48 At.%. The best magnetic properties have been observed when the annealing temperature is close to 575°C. Temperature dependence of real part of initial permeability of the annealed samples between the annealing temperature of 550°C and 575°C exhibits superparamagnetic/superferromagnetic behaviour at T >.

Keywords: Amorphous alloy, Finemet, Magnetic properties, Nanocrystalline alloy, Superferromagnetism

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 300-305

 

 

Field dependent soft mode frequency in BaxSr1-xTiO3 ferroelectric perovskites

Ashok Kumar, Ashish Kukreti* & U C Naithani

Department of Physics, Garhwal University Pauri, Campus Pauri (Garhwal) Uttarakhand 246 001

E-mail: ashishkukreti07@gmail .com

Received 29 July 2008; revised 19 January 2009; accepted 3 March 2009

An expression has been obtained for the soft mode frequency in BaxSr1-xTiO3 ferroelectric perovskites in the presence of external electric field, by using double time temperature dependent Green’s function technique. The mass and force constant change due to impurity atoms which are taken into account in the presence of higher order anharmonic and electric moment terms in the Silverman Joseph Hamiltonian. The soft mode frequency is obtained in the presence of both the electric field and impurity of Ba in an anharmonic SrTiO3 ferroelectric perovskites. The soft mode frequency decreases with increase of impurity concentration of Ba in pure SrTiO3 . The soft mode frequency also increases with increase of external electric field in BaXSr1-XTiO3 ferroelectric perovskites.

Keywords: Soft mode frequency, Ferroelectric perovskites, Green’s function, Anharmonicity

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 306-309

 

 

New low-voltage class AB current conveyor II for analog applications

Parshotam S Manhas*, K Pal**, Susheel Sharma*, L K Mangotra* & K K S Jamwal***

*Department of Physics & Electronics, University of Jammu, Jammu 180 006

**Department of Earthquake Engineering, IIT Roorkee, Roorkee

***Department of Physics, University of Kashmir, Srinagar, 190 006

Received 4 September 2008; accepted 9 January 2009

Current conveyors are unity gain active elements exhibiting high linearity, wide dynamic range and high frequency performance than their voltage mode counterparts. The new current conveyor operating at low-voltage supplies high input impedance and low output impedance and consumes less power. In this study, a new low-voltage class AB second generation current conveyor (AB CCII) is presented which can be easily converted into CFAs, etc. PSpice simulation results verifying theoretical analysis are also incorporated.

Keywords: Low-voltage circuit, Current conveyor, Analogue integrated circuits

 

 

Indian Journal of Pure & Applied Physics

Vol. 47, April 2009, pp. 310-316

 

 

Performance of non-linear amplifier based phase locked loop systems in
presence of channel perturbations

 

B De+ & B C Sarkar*

+Physics Department, Presidency College, Kolkata 700 073

*Physics Department, Burdwan University, Burdwan 713 104

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

Received 16 June 2008; accepted 29 December 2008

The tracking performance of non-linear amplifier based conventional second order phase locked loop (PLL) and charge pump phase locked loop have been examined numerically by solving the system equations in the presence of lognormal type of fading signal. Some analytical results for non-linear amplifier based conventional phase locked loop and charge pump phase locked loop are also incorporated to confirm the simulation results and for the choice of optimum design system parameter.

Keywords:   Non-linear amplifier, Phase locked loop, Signal