Indian Journal of Pure and Applied Physics

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Volume 46

Number 11

NOVEMBER 2008

CODEN : IJOPAU 46 (11) 749- 818

ISSN: 0019-5596

 

 

 

CONTENTS

 

Nuclear Physics

 

Calculation of power density distribution in miniature neutron source detector using the MTR_PC V2.6 code package

755

I Khamis* & N Ghazi

 

 

 

Atomic and Molecular Physics

 

Determination of accuracy of particle size by acoustic scattering using a modified Born approximation

761

Ratan K Saha & Subodh K Sharma*

 

 

 

Condensed Matter:Structural , Mechanical and Thermal Properties

 

Study of thermal properties of nickel using embedded-atom-method

771

S S Hayat* , M A Choudhury, S A Ahmad, J I Akhter & Altaf Hussain

 

 

Effect of carbon content on the mechanical properties of ternary boron-nitrogen-carbon compound

776

M Pal Chowdhury, S Dalui, B R Chakraborty , A Mukherjee & A K Pal*

 

 

Diamond and diamond like carbon in laser heated diamond anvil cell at 16.5 GPa and above 2000K from pyrolitic graphite

783

N R Sanjay Kumar*, N V Chandra Shekar, M Sekar, N Subramanian, P Chandra Mohan,

M P Srinavasan, P Parameswaran & P Ch Sahu

 

 

 

Zone center phonon frequencies for inverse spinel structure compounds

788

A K Kushwaha

 

 

 

Effect of growth parameters on structural, electrical and optical properties of titanium oxide thin films

791

S Sankar & K G Gopchandran*

 

 

 

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

 

Effect of hydrogen and nitrogen incorporation on the properties of tetrahedral amorphous carbon films grown using S bend filtered cathodic vaccum arc process

797

O S Panwar*, Mohd Alim Khan, G Bhagavanarayana, P N Dixit , Sushil Kumar & C M S Rauthan

 

 

Optical band gap of In0.1Bi1.9Te3 thin films

806

P H Soni*, S R Bhavsar, G R Pandya & C F Desai

 

 

 

Charge carrier injection and extraction at metal dielectric contact under an applied electric field

809

Eugen R Neagu

 

 

____________

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

 

 

 

 

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 755-760

 

 

Calculation of power density distribution in miniature neutron source detector using the MTR_PC V2.6 code package

I Khamis & N Ghazi

Department of Nuclear Engineering, Atomic Energy Commission, P.O. Box 6091-Damascus, Syria

Received 30 July 2007; revised 12 June 2008; accepted 22 July 2008

Spatial power distribution for the miniature neutron source detector (MNSR) has been calculated and presented as a function of the three coordinates. Accordingly, the MNSR Safety Analysis Report will be amended with the obtained information. The spatial power distribution has shown a maximum value for power density attained in the MNSR and reaches 3.24 w/cm3, located near the core center in case where the control rod is fully withdrawn. The effect of the control rod position on such power space-distribution in all 3-axis and various location of the control rod in the core were analyzed. Total, axial and radial peak power factors have been calculated. Their values were 1.27, 1.14 and 1.116, respectively. The Argentinean MTR_PC V2.6 code package was installed and utilized for various applications, especially, neutronics calculations for nuclear research reactors. Finally, the package was verified and utilized it through the calculations of both delayed neutron fraction and the prompt neutron generation time for the MNSR. The obtained values for these two parameters were 7.8673E-03 and 8.1534E-05 s, respectively. These parameters were calculated using the core calculation code CITVAP i.e. CITATION, having the microscopic cross-section library obtained by the code BORGES based on the cell calculation WIMS code. The presented results are in a very close agreement with the published results.

Keywords:Power distribution, MNSR, MTR_PC, Codes, Neutronics calculations, WIMS, CITVAP

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 761-770

 

 

Determination of accuracy of particle size by acoustic scattering using a modified Born approximation

Ratan K Saha*

LBUM-CRCHUM, University of Montreal, Canada

and

Subodh K Sharma

Satyendra Nath Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098

Received 1 November 2007; accepted 16 May 2008

Accuracy of a recently proposed modified Born approximation (MBA) has been examined for size determination of an isolated scatterer. Two methods have been employed for this purpose. One is based on the analysis of the angular scattering pattern of plane waves and the other on analysis of the power spectrum of the backscattered pulse. In each case, domain of validity of the modified Born approximation for size determination has been assessed for two exactly soluble test models, namely, the scattering by a sphere and an infinitely long cylinder. For completeness, comparisons with conventional Born approximation (BA) results have also been made. The performances of the approximations have been examined for scatterers whose size parameters vary over a range 3 to 75. Mismatches of the density and compressibility are less than 15% in these calculations. Numerical results show that MBA indeed has a larger validity domain in comparison to BA for an intermediate size weak scatterer.

Keywords: Acoustic waves, Scattering, Born approximation, Particle sizing

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 771-775

 

 

Study of thermal properties of nickel using embedded-atom-method

 

S S Hayat*, M A Choudhry, S A Ahmad, J I Akhter+ & Altaf Hussain

Departmenrt of Physics, The Islamia University of Bahawalpur, Bahawalpur 63120, Pakistan

+Physics Division, Pakistan Institute of Nuclear Science & Technology, PO Nilore, Islamabad, Pakistan

*E-mail: sikandariub@yahoo.com

Received 12 May 2008; accepted 28 August 2008

Thermal properties of metals and alloys have been studied for a long due to their importance in the materials design. Molecular dynamics simulation technique is applied to investigate thermal properties of Ni. Semi-empirical potentials based on the Embedded Atom Method (EAM) have been employed to calculate lattice parameter, energy per atom, mean square displacements and radial distribution function. Thermal properties like specific heat, thermal coefficient of linear expansion and melting temperature are deduced from the calculated parameters. The results are found to compare well with the experimental results.

Keywords: Molecular dynamics simulation; Thermal properties; Nickel metal

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 776-782

 

 

Effect of carbon content on the mechanical properties of ternary boron-nitrogen-carbon compound

M Pal Chowdhury, S Dalui, B R Chakrabortya, A Mukherjeeb & A K Pal*

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

aNational Physical Laboratory, New Delhi

bCentral Glass & Ceramic Research Institute, Calcutta 700 032

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

Received 6 June 2008; revised 29 August 2008; accepted 24 October 2008

BNC films have been deposited on Si (100) and fused silica substrates by inductively coupled plasma chemical vapour deposition (ICP-CVD) technique using a mixture of borane-ammonia, nitrogen and methane as precursor gases. Carbon content in the films is varied by changing the concentration of methane in the precursor gases. The films are amorphous in nature. The films, thus, deposited have been characterized by using Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction and Secondary Ion Mass Spectroscopy (SIMS). Microstructural information has been obtained from SEM studies. Microhardness has been seen to decrease with the increase in carbon content and the highest microhardness observed in these films has been found to be~5.3 GPa.

Keywords: BNC films, Hard coatings, Chemical vapour deposition

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 783-787

 

 

Diamond and diamond-like carbon in laser heated diamond anvil cell at 16.5 GPa and above 2000 K from pyrolitic graphite

N R Sanjay Kumar, N V Chandra Shekar, M Sekar, N Subramanian, P Chandra Mohan#,
M P Srinivasan#, P Parameswaran* & P Ch Sahu

Materials Science Division,*Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102

#Water and Steam Chemistry Division, BARC Facility, IGCAR, Kalpakkam 603 102

Received 14 May 2008; revised 25 August 2008; accepted 20 October 2008

Diamond and diamond like carbon have been synthesized by direct conversion of pyrolitic carbon at pressure, 16.5 GPa and temperature, ~ 2000 K using a Laser Heated Diamond Anvil Cell (LHDAC) facility. The formation of diamond and diamond like carbon is confirmed by micro-Raman and scanning electron microscopy. The synthesised material has been found as opaque and colourless. The diamond crystals formed in this process are of micrometer size having regular facets. In this experiment, the diamond formation pressure is much lower than reported in shock pressure experiments.

Keywords: Pyrolytic graphite, Synthesis of diamond, Diamond anvil cell, Laser heating, Micro-Raman, Scanning electron
image

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 788-790

 

 

Zone-centre phonon frequencies for inverse spinel structure compounds

A K Kushwaha

Department of Physics, KN Government PG College, Gyanpur, Bhadohi-221 304, India

E-mail: akkphys_bu@yahoomail.com

Received 9 October 2007; accepted 25 August 2008

The zone-centre infrared and Raman phonon modes for the inverse spinel structure compounds MIn2S4 (M = Fe and Ni) have been calculated by using the rigid-ion model. The interatomic interaction in the octahedral bonding is stronger than the interatomic interaction in the tetrahedral bonding. It is also found that the compound NiIn2S4 is more ionic in comparison to FeIn2S4.

Keywords: Inverse spinel compounds, Zone-centre, Phonons, Tetrahedral and octahedral, Effective charges

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 791-796

 

 

Effect of growth parameters on structural, electrical and optical properties of titanium oxide thin films

 

S Sankar & K G Gopchandran*

Department of Optoelectronics, University of Kerala, Kariavattom, Thiruvananthapuram 695 581

*E-mail: gopchandran@yahoo.com

Received 11 March 2008; revised 18 August 2008; accepted 10 October 2008

Semi-transparent and highly conducting nanostructured titanium oxide thin films have been prepared using pulsed laser deposition technique. Films deposited on quartz substrates, kept at 773 K, are shown to have resistivity of 2.910-4 Wm and a maximum optical transmittance of 50%. The characterizations of the films are done with X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, UV-visible spectroscopy and conductivity measurements. Eventhough annealing transformed the films from amorphous to nanocrystalline phase with preferential growth along (110) plane of the rutile TiO2, the grain size as well as the voids between the grains after transformation, have been seen to be governed by the kinetics and thermodynamics during deposition of the films. The optical transmittances of the films have been found to increase with annealing temperature. Optical constants are derived from the transmission spectra and the refractive index dispersion has been discussed in terms of the single oscillator-Wemple and Didomenico model.

Keywords: Titanium oxide films, Thin films, Optical constant, Optical transmittance

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 797-805

 

 

Effect of hydrogen and nitrogen incorporation on the properties
of tetrahedral amorphous carbon films grown using S bend
filtered cathodic vacuum arc process

 

O S Panwara*, Mohd Alim Khana, G Bhagavanarayanab, P N Dixita, Sushil Kumara & C M S Rauthana

aPlasma Processed Materials Group, National Physical Laboratory, Dr K S Krishnan Road, New Delhi110 012

bMaterial Characterization Division, National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110 012

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

Received 26 February 2008; revised 1 July 2008; accepted 6 August 2008

The electrical and mechanical properties of as- grown and also hydrogen and nitrogen incorporated tetrahedral amorphous carbon (ta-C) films, deposited using S bend filtered cathodic vacuum arc process have been reported. First, the effect of varying negative substrate bias on the dark conductivity (sD), activation energy (ΔE1) and residual stress of as grown ta-C films and next the effect of varying hydrogen and nitrogen partial pressure on the properties of ta-C: H and ta-C: N films deposited at a high negative substrate bias of -300V are reported. The value of sD is minimum at 10-4 ohm -1cm-1 in as- grown ta-C films deposited at -150V substrate bias whereas the value of ΔE1 is maximum at 0.22 eV and residual stress is maximum at 0.71 GPa in as- grown ta-C films deposited at -200 V applied substrate bias and it is found to depend on the substrate bias. Hydrogen incorporation in ta-C films decreases the value of sD to 1.010-9 ohm -1cm-1, increases the values of ΔE1 to 0.45 eV continuously with the increase of hydrogen partial pressure up to 1.410-3 mbar whereas nitrogen incorporation in ta-C films increases the value of sD to 10-1 ohm -1cm-1 and decreases the value of ΔE1 to 0.07 eV continuously with the increase of nitrogen content up to 16.3 at. %. Low amount of hydrogen incorporation in ta-C films up to 7.410-5mbar hydrogen partial pressure reduces the value of residual stress and larger amount of hydrogen incorporation beyond this pressure increases the value of residual stress whereas nitrogen incorporation in ta-C films reduces the values of residual stress. The effect of hydrogen on ta-C is to give a modest gain in semi-conducting properties by passivating some defect states whereas the effect of nitrogen gives n-type doping effect in ta-C films.

Keywords: Conductivity, Activation energy, Residual stress, ta-C, ta-C: H, ta-C: N, FCVA

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 806-808

 

 

Optical band gap of In0.1Bi1.9Te3 thin films

P H Soni, S R Bhavsar, G R Pandya & C F Desai

Department of Physics, Faculty of Science,The M S University of Baroda, Vadodara 390 002

Received 23 April 2007; revised 24 January 2008; accepted 30 May 2008

Thin films (In0.1Bi1.9Te3 ) were grown using the thermal evaporation technique on a (001) face of NaCl crystal as a substrate at room temperature. The optical absorption was measured in the wave number range 500-4000 cm-1. From the optical absorption data, the band gap has been evaluated and studied as a function of the film thickness and deposition temperature. The band gap increases with decreasing thickness, a result normally associated with quantum size effect. The deposition temperature does not seem to affect the band gap as indicated by the results. The data indicate absorption through direct interband transition with a band gap around 0.14 eV.

Keywords: Absorbance, Band gap, Film thickness, Size effect

 

 

Indian Journal of Pure and Applied Physics

Vol.46, November 2008, pp 809-814

 

 

Charge-carrier injection and extraction at metal-dielectric contact under an
applied electric field

Eugen R Neagu

Department of Physics, Technical University of Iasi, B-dul D. Mangeron N. 67 Iasi-700050, Romania

E-mail: euneagu1@yahoo.com

Received 4 March 2008; revised 26 August 2008; accepted 1 September 2008

There is charge injection/extraction at a metal-dielectric contact. In general, the problem is treated by analogy with that for metal-semiconductor contact. However, the electrical conduction through dielectrics is bulk and electrode limited. Consequently, it is difficult to discriminate between the two effects and to have specific information only about one of the mechanisms. We propose a method that allows to determinate the sign and the value of the electric charge injected/extracted at the metal-dielectric contact. The method is based on the modification of the external electric field of a dielectric when electric charge is injected/extracted onto its surface. The lowest surface charge density measured in the presented experiments was around 1.8 10-6 cm-2 which corresponds to a medium distance of about 300 nm between two trapped charges. The injection/extraction process takes place no matter if there is a conduction current through the sample.

Keywords: Dielectrics, Metal-dielectric contact, Charge injection/extraction, Traps

 

 

 

 

Author Index


 

 

Keyword Index