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Indian Journal of Pure and Applied Physics

 

 

 

ISSN: 0019-5596

CODEN: IJOPAU 43 (2) 73-150

Volume 43

Number 2

FEBRUARY 2005

 

 

CONTENTS

 

Atomic and Molecular Physics

Infrared spectroscopic study of phase transitions in natural scolecite

79

K Shiva Prasad, P S R Prasad* & S R Sharma

Systematization of L X-ray satellites II: Lb2 and Lg satellites

83

U D Misra* & N Kumar 

Infrared study of the effect of P2O5 in the structure of lead silicate glasses

89

M Rafiqul Ahsan*, M Alfaz Uddin & M Golam Mortuza

Luminescence studies of SrS and CaS based phosphors

100

Vijay Singh, Manoj Tiwari*& S J Dhoble

Condensed Matter:Structural, Mechanical and Thermal Properties

Hall coefficient and coefficient of transverse magneto- resistance in intermediately doped n-type silicon with mixed scattering

 104

Tesfaye Getinet

Lattice dynamics of pnictides and chalcogenides

109

Mahendra Aynyas*, P K Jha & Sankar P Sanyal

Transparent carbon coatings of ultra fine diamond

115

T N Patrusheva*, A Ya Koretz & E M Mironov

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

Mössbauer , X-ray and magnetization studies of basic volcanic and hyperbasal rocks

119

Roshan Lal, N D Sharma*, S P Taneja & Kailash Chandra

Electrical conductivity and dielectric measurements in Au+ doped/undoped KDP crystals with KCl and NaCl as additives

123

R Ananda Kumari* & R Chandramani

Variation of optical band gap in obliquely deposited selenium thin films

129

M Singh*, K C Bhahada, & Y K Vijay

Thermal conductivity, diffusivity and heat capacity of plasticized polyvinyl chloride

132

P Dashora*, G Gupta & J Dashora

Electrical conduction in potassium boro-vanadate iron glass

137

Harshvadan R Panchal & Dinesh K Kanchan*

Interdisciplinary Physics and Related Areas of Science and Technology

Current-mode universal biquadratic filter with single input and four outputs using FTFNs

142

N A Shah* & M A Malik

 

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


 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 79-82

 

 Infrared spectroscopic study of phase transitions in natural scolecite

 K Shiva Prasad, P S R Prasad* & S R Sharma

In-situ infrared spectroscopic (FTIR) studies are carried out on a naturally occurring scolecite, from Deccan traps, in the temperature range 300-850 K. Five bands are observed at 3589, 3507, 3409, 3327, and 3232 cm-1 in the (OH) stretching mode region, and three bands at 1665, 1649 and 1591 cm-1 in the bending mode region indicating a more complex molecular interaction between H2O and network cations in scolecite. At around 500 K, stretching mode region is replaced with three band structure, and the bending mode region with a band around 1658 cm-1, indicating partial dehydration in scolecite. At around 720 K complete disappearance of infrared modes due to water molecules indicates total dehydration. X-ray diffraction (XRD) of the sample corroborates the transformation to amorphous phase at higher temperatures.

[Keywords: Zeolites, Scolecite, Dehydration, FTIR]

IPC Code: G01J 3/00

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 83-88

 Systematization of L X-ray satellites II: Lb2 and Lg satellites

 U D Misra & N Kumar

By the use of the method of iteration, based on Hagström's doubly modified Moseley plot, the wavelengths of a large number Lb2 and Lg satellite lines in the atomic number range Z=39 to 80 have been calculated. This has resulted in the removal of anomalies in the measurement of the wavelengths of some of these satellites. A number of experimentally measured satellites have been identified for the first time as a result of our calculations, while in other cases, erroneous identifications by earlier researchers have been corrected.

[Keyword: L X-ray satellites, Lg satellites, Moseley plot]

IPC Code: G01J 3/443

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 89-99

  Infrared study of the effect of P2O5 in the structure of lead silicate glasses

 M Rafiqul Ahsan, M Alfaz Uddin & M Golam Mortuza

The infrared spectra of xPbO (1-x-z)SiO2zP2O5 glasses with a PbO:SiO2 molar ratio of 3:2 and z=0,1,2,5,30,40 and 50 mol% have been examined in the region 4000-400 cm-1, together with XRD. The structure of PbO-SiO2 binary glass is significantly different from that of P2O5 substituted glasses. The low amount of P2O5 containing PbO-SiO2 glasses results in infrared spectra of the same pattern as 3:2 binary lead silica glass but the maximum peak intensities and positions are different. The spectra of high P2O5 (30-50 mol%) containing glasses show an increased number of distinct peaks in the low frequency region with a convolution of several broad Gaussians in the high frequency region. All the spectra are base line corrected and deconvoluted to appropriate number of Gaussians. The peaks and peak positions of the Gaussians are assigned to Si-O-Si, Si-O-Pb, Si-O-P, P-O-P, O-P-O, P=O, P-O- etc. bonds. A variation in the band positions and the relative amounts of bonds with P2O5 is also shown. The result indicates that ortho- and pyro-phosphate are formed around 1-5 mol% P2O5 containing glasses and meta-phosphate species from the high P2O5 containing glasses. The ionic character of the phosphate groups P-O-, PO43- is well revealed by the formation of new band within 1250-900 cm-1. The incorporation of high contents of P2O5 in the materials suggests that P5+ occupies the network position and forms the linkage Si-O-P in the glasses. This Si-O-P bond may lead to the formation of five and six coordinated silicon in the glass matrix. X-ray diffraction pattern of the base samples, within the detection limit, shows that all are homogeneous glasses and these have not shown any evidence of phase separation on optical inspection.

[Keywords: Infrared spectra, Lead silicate glasses, PbO-SiO2, Binary glass, P2O5]

IPC Code: G01J 3/00

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 100-103

 Luminescence studies of SrS and CaS based phosphors

 Vijay Singh, Manoj Tiwari & S J Dhoble

Sulphide based phosphors activated with Bi and Mn ions were prepared by solid-state diffusion method. The emission and excitation spectra of SrS:Bi, SrS:Mn and SrS:Bi, Mn phosphors were recorded at room temperature due to their photoluminescence characterization as well as the energy transfer process. The photoluminescence study of phosphors shows the energy transfer from Bi3+ to Mn2+. The thermo luminescence study of CaS:Mn and CaS:Bi was also carried out.

[Keywords: Photoluminescence, Thermoluminescence, Sulphide phosphors]

 

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 104-108

 Hall coefficient and coefficient of transverse magneto-resistance of intermediately doped n-type silicon with mixed scattering

 Tesfaye Getinet

The explicit expressions for Hall coefficient and coefficient of transverse magneto-resistance in an intermediately doped n-type silicon with mixed scattering of electrons by both ionized impurities as well as acoustic phonons by using the modified density of states function have been derived. These explicit expressions are used to numerically calculate the dimensionless Hall coefficient and coefficient of transverse magneto resistance for different doping concentrations at room temperature. By using the modified density of states function changes the coefficients by as much as 62% and 11% for the normalized Hall coefficient and coefficient of transverse magneto resistance, respectively at room temperature when compared with the corresponding calculations obtained by using the parabolic density of states function.

[Keywords: Hall coefficient, n-Type silicon, Magneto-resistance, Acoustic phonons]

IP Code:H03B 15/00

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 109-114

 Lattice dynamics of thorium pnictides and chalcogenides

 Mahendra Aynyas, P K Jha & Sankar P Sanyal

The phonon spectra of thorium pnictides and chalcogenides (ThX) have been analysed using rigid ion and breathing shell models, in view of their structural properties at high pressure. The significance of these two approaches in predicting the dynamical properties of ThX compounds has been discussed and the role of f-electron has been examined. The dominant ionic nature of bonding has been predicted for ThX compound from the large LO-TO phonon splitting at zone centre. The low temperature specific heat for these compounds has been reported.

[Keywords: Lattice dynamics, Thorium pnictides, Chalcogenides, Phonon spectra]

IPC Code: B01D 9/00

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 115-118

 Transparent carbon coatings of ultra fine diamond

T N Patrusheva, A Ya Koretz & E M Mironov

Low-temperature method for depositing ultra fine diamond (UFD) films by a simple wet chemical route is presented. The UFD is produced from detonation synthesis of explosive substances. These nano-sized diamond particles under specific conditions formed stable suspension with analogous properties as sols. The organic suspensions of UFD had low values of surface tension and could easily wet different substrates to form films by dipping technique. The surface of the substrates and the effects of the organic medium stimulated a structural organization. The action of different forces during wetting caused the desegregation of particles, which culminated in even distribution on the substrate. The spectral investigation in UV-VIS-IR region showed that the films had diamond-like optical properties. It was found that glasses became more transparent with these UFD coatings on them. Efficiency of cutting tools was also found to increase significantly with the use of UFD coating on them.

[Keywords : Ultra fine diamond, Organic suspension, Wetting films]

IPC Code : G01N

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2004, pp. 119-122

 Mössbauer, X-ray and magnetization studies of basic volcanic and hyperbasal rocks

Roshan Lal, N D Sharma, S P Taneja & Kailash Chandra

 

The 57Fe Mössbauer, X-ray diffraction and magnetic susceptibility studies were carried on two samples, basic volcanic (basalt) and hyperbasal (dolerite) rocks, collected from Kundal area of Rajasthan, India to identify iron-bearing minerals. Room temperature Mössbauer parameters of basalt sample show the presence of hematite (Fe2O3), aluminium substituted magnesioferrite [Mg(Fe2-xAlx)O4] and illite. Iron is present as both Fe3+ and Fe2+ in illite. Temperature dependence of magnetic susceptibility measurements shows no transition around 120 K (Verway transition) for both the samples, indicating existence of (Mg, Al) substituted spinel ferrites. These results have been corroborated by X-diffraction and chemical analysis of the samples.

 

[Keyword: Mössbauer parameters, Magnetic susceptibility, Mössbauer spectroscopy, X-ray diffraction]

IPC Code: G01N 23/00, 24/00

 

 

 

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp 123-128

 

Electrical conductivity and dielectric measurements in Au+ doped/undoped KDP crystals with KCl and NaCl as additives

R Ananda Kumari & R Chandramani

 

Pure potassium dihydrogen orthophosphate (KDP) containing KCl or NaCl with and without gold doping were grown by slow evaporation technique. All the grown crystals were g-irradiated using 60Co source. Electrical conductivity measurements were carried out perpendicular to the unique direction before and after g-irradiation. The conductivity of KDP crystals increases with the addition of KCl and NaCl and with gold doping as well as temperature. Computed values of activation energies from the conductivity measurements are given. The dielectric constant and dielectric loss have been measured as a function of frequency. The study confirms the contribution of space charge polarization.

 

[Keywords: KDP crystals, Doping, Dielectric constant, Electrical conductivity, Activation energy]

IPC Code: H01 L 41/00

 

 

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp 129-131

 
Variation of optical band gap in obliquely deposited selenium thin films

M Singh, K C Bhahada & Y K Vijay

 

The selenium thin films of obliquely and normal deposited for different thickness were prepared using thermal evaporation method at pressure of 10- 5torr on to the glass substrate at room temperature. The band gap of thin films with respect to normal to vapour beam direction decreases with angle of deposition, which may be due to small increase in the thickness of the thin films with angle of deposition. The optical band gap has also been observed for different thin films having large variation in thickness.The optical energy band gap of these films decreases with thickness due to quantum size effect.

 

[Keywords: Optical band gap, Selenium thin films]

IPC Code: B 05D 5/06

 

 

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 132-136

 

  

Thermal conductivity, diffusivity and heat capacity of plasticized polyvinyl chloride

 P Dashora, G Gupta & J Dashora

 

Simple formalisms for thermal conductivity l, thermal diffusivity D and specific heat Cp of both linear and cross-linked amorphous polymers has been presented. These relations explain successfully the dependence of these properties on temperature and amount of plasticizer. Present study reveals that the santicizer-160 forms cross-linkage among the linear chains of polyvinyl chloride (PVC). The structural transition at Tg, the anti-plasticization effect below Tg and plasticization effect above Tg, are clearly reflected in the trends of these properties. The calculated values of all the three properties for PVC plasticized with different amount of plasticizer (Santicizer-160: 10 phr, 20 phr and 30 phr) are in excellent agreement with the experimental values over a wide range of temperature, which includes glassy, leathery and rubbery regions. The maximum deviation in experimental and calculated values is less than 5% for all these properties.

 

[Keywords: Thermal conductivity, Diffusivity, Heat capacity, Plasticized polyvinyl chloride]

IPC Code: B01N 25/18

 

 

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp 137-141

 

Electrical conduction in potassium boro-vanadate iron glass

Harshvadan R Panchal & Dinesh K Kanchan

 

The conduction mechanism of xK2O:(100-x-y)[(1+n)V2O5:B2O3]:yFe2O3 where x = 0,5,10,15, 20, y = 5, 7.5, 10, 12.5 and 15 and n = 0.2 to 1 in step of 0.2 had been explained on the basis of Mott’s theory. The dc conductivity of the present glass system was measured in the temperature range 315-435 K for all the different glass compositions. The decrease of conductivity and increase in activation energy had been observed with the increase of Fe2O3 concentration. Estimated small polaron radius is found to be smaller than the atomic site spacing (V-V spacing) and greater than the radius of iron on which the electron is localized. The present glass system shows a semiconducting adiabatic hopping due to a small polaron.

 

[Keywords: Electrical conductivity, Polaron, Activation energy]

IPC Code: G 01 R

 

 

Indian Journal of Pure & Applied Physics Vol. 43, February 2005, pp. 142-144

 

Current-mode universal biquadratic filter with single input and four outputs using FTFNs

N A Shah & M A Malik


A novel four terminal floating nullor (FTFN) based universal current-mode (CM) biquadratic filter configuration with single input and four outputs (SIFO) is presented. The circuit is based on and employs six FTFNs of the same polarity and as many passive components and realizes simultaneously lowpass (LP), highpass (HP), inverted bandpass (BP) and Notch filtering functions without any imposition of component matching conditions or cancellation constraints. The circuit can also be made to realize allpass (AP) response by tying together appropriate output filtering signals. The topology has the distinct feature of low input and high output impedances which permits easy cascading for the construction of higher order filters. The circuit enjoys low passive sensitivity figures. The resonance frequency wo and bandwidth wo/Q can be independently tuned while as resonance frequency wo and quality factor Q can be orthogonally adjusted. Experimental and PSPICE simulation results are given to confirm the theoretical results.

 

[Keywords: Universal filter, Biquadratic filters, Current-mode filters, Four terminal floating nullors, Filtering functions]

IPC Code: H 03 K 3/00