VP and RPTP Science College

Vallabh Vidyanagar, India

VP and RPTP Science College

Vallabh Vidyanagar, India
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Vinodkumar M.,VP and RPTP Science College | Desai H.,Sardar Patel University | Vinodkumar P.C.,Sardar Patel University | Mason N.,Open University Milton Keynes
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

A detailed theoretical study is carried out for electron interactions with magnesium oxide (MgO) with incident energies ranging from 0.01 to 5000 eV. This wide range of energy has allowed us to investigate a variety of processes and report data on resonances through eigenphase study, vertical electronic excitation energies, differential, momentum transfer, and total cross sections (TCS), as well as scattering rate coefficients. MgO has a large number of low-lying π excited states and the present study finds overall a good agreement with earlier reported data. In order to compute total cross sections, we have employed the ab initio R-matrix method (0.01 to ∼20 eV) and the spherical complex optical potential method (∼20 to 5000 eV). The R-matrix calculations are performed using a close-coupling method with the aid of 34 target states, 1436 configuration state functions, and 213 channels employing a static exchange plus polarization model. The present study reports evidence for electron scattering resonances through analysis of eigenphase diagrams at low energies below the ionization threshold. In the absence of any theoretical or experimental data for resonances, we have done double differentiation of TCS to confirm the resonances reported here. The present study is a maiden effort to report excitation cross sections, differential cross sections, momentum transfer cross sections, and scattering rate coefficients at low energies below the ionization threshold of the target. Additionally, in the absence of any experimental data and sparse theoretical data for a total elastic cross section, the present comprehensive study will provide a reference data set over such an extensive impact energy range. © 2016 American Physical Society.


Jivani A.R.,VP and RPTP Science College | Jani A.R.,Sardar Patel University
International Journal of Modern Physics B | Year: 2011

The higher-order perturbation theory based on pseudopotential approach is used to investigate few elastic and vibrational properties of Group IV semiconductors. The homogeneous deformation method is used to calculate elastic constants. To consider electron-ion interactions, our own proposed potential is employed to investigate such properties of Si, Ge and α-Sn. The potential contains only single parameter and its value is determined by fitting experimental value of bulk modulus. The calculated physical properties like elastic constants, pressure derivatives of the bulk modulus, pressure derivatives of elastic constants, Young's modulus and Poisson's ratio etc., of Si, Ge and α-Sn are in good agreement with available experimental and other available theoretical results. The deviation of the present calculations using our potential with respect to experimental data is found to be less than 10% in most of the calculated physical properties. To consider the exchange and correlation effect, five different local-field correction functions are incorporated in the present investigations. From the present study, it can be observed that incorporation of local-field correction and the covalent-correction term are important in such type of investigations. © 2011 World Scientific Publishing Company.


Jivani A.R.,VP and RPTP Science College | Jani A.R.,Sardar Patel University
Advanced Materials Research | Year: 2013

In the present investigation, we report theoretical study of total energy, energy band gap in X-direction, bulk modulus, elastic constants and pressure derivative of elastic constants of Si1-xSnxsolid solution using higher-order perturbation theory along with application of our proposed potential, where x is concentration of Sn. The parameter of our potential is determined using zero-pressure equilibrium condition. In the present calculations, The local-field correction function can be employed to consider exchange and correlation effects. The present study showed that the physical quantities under investigation varied with the concentration of the constituent element. © (2013) Trans Tech Publications, Switzerland.


Jivani A.R.,VP and RPTP Science College | Jani A.R.,Sardar Patel University
Turkish Journal of Physics | Year: 2012

The static elastic constants (C 11, C 12 and C 44) , pressure derivative of elastic constants, pressure derivative of bulk modulus, propagation velocities of longitudinal and transverse waves in [100], [110] and [111] directions and Young modulus are investigated through computations using the higher-order perturbation theory based on pseudopotential formalism, in which we have applied our own proposed model potential for GaP, GaAs and GaSb semiconductor compounds. In the present calculations, two local-field correction functions are employed to consider exchange and correlation effects. The numerical values of the aforesaid properties are found to be sensitive to the selection of the local-field correction function and showing a significant variation with the change in the function. The presently investigated numerical data is found to have, in general, good agreement with the available experiment data and other such theoretical values. © TÜBITAK.


Jivani A.R.,VP and RPTP Science College | Jani A.R.,Sardar Patel University
Indian Journal of Physics | Year: 2016

The cohesive energy, bulk modulus, elastic constants, pressure derivative of bulk modulus and pressure derivative of elastic constants for InxGa1−xNyAs1−y semiconducting quaternary alloys have been investigated based on pseudopotential formalism. A reasonable agreement of presently investigated numerical data with the available experimental data and other such theoretical values has been observed. © 2015, Indian Association for the Cultivation of Science.


Jivani A.R.,VP and RPTP Science College | Jani A.R.,Sardar Patel University
International Journal of Modern Physics B | Year: 2015

Physical properties like elastic constants, pressure derivative of bulk modulus, pressure derivative of elastic constants and acoustic wave velocities in different directions for MgxZn1-xS, MgxZn1-xSe and ZnSySe1-y semiconductor ternary alloys and MgxZn1-xSySe1-y quaternary alloys with different concentrations of x and y are studied using our previously proposed potential based on the pseudopotential formalism. It is noticed from the present study that the physical properties under investigations depend on concentrations x and y of constitute compounds. The present results of various physical quantities of compounds presented here are compared with the available experimental data and other theoretical estimations and showed roughly reasonable agreement. The numerical values of same quantities for ternary alloys and MgZnSSe quaternary alloys were reported first time and hence such results may be useful for comparison purpose in future with either the experimental or the theoretical work. © 2015 World Scientific Publishing Company.


Jivani A.R.,VP and RPTP Science College | Baria J.K.,VP and RPTP Science College | Vyas P.S.,VP and RPTP Science College | Jani A.R.,Sardar Patel University
AIP Conference Proceedings | Year: 2013

Elastic properties of Si1-xGex solid solution with arbitrary (atomic) concentration (x) are studied using the pseudo-alloy atom model based on the pseudopotential theory and on the higher-order perturbation scheme with the application of our own proposed model potential. We have used local-field correction function proposed by Sarkar et al to study Si-Ge system. The Elastic constants and pressure derivatives of elastic constants of the solid solution is investigated with different concentration x of Ge. It is found in the present study that the calculated numerical values of the aforesaid physical properties of Si-Ge system are function of x. The elastic constants (C 11, C12 and C44) decrease linearly with increase in concentration x and pressure derivative of elastic constants (C 11, C12 and C44) increase with the concentration x of Ge. This study provides better set of theoretical results for such solid solution for further comparison either with theoretical or experimental results. © 2013 American Institute of Physics.


Parab R.H.,VP and RPTP Science College | Patel K.D.,VP and RPTP Science College | Desai D.J.,P M Patel Institute Of Post Graduate Research In Science | Dixit B.C.,VP and RPTP Science College
Journal of Saudi Chemical Society | Year: 2012

The present communication aims to develop bisazo disperse dyes based on 3-[4-(4-amino-2-chlorophenoxy)anilino]phenol (DAP) both as a coupling component as well as a diazonium salt. Coupling reaction of DAP was carried out with a diazonium salt of 4-aminoacetanilide to yield a monoazo disperse dye, and then it was further used as a diazonium salt and coupled with a different aromatic phenol to synthesize bisazo disperse dyes. All the disperse dyes were characterized by elemental analysis, IR, NMR and UV-Visible spectral studies with a view to determine their chemical structure. The dyeing ability of these bisazo disperse dyes has been evaluated in terms of their dyeing behavior and fastness properties on different fabrics. © 2012.


SnS (tin sulphide) is of interest for use as an absorber layer and the wider energy band gap phases e.g. SnS2, Sn2S3 and Sn/S/O alloys of interest as Cd-free buffer layers for use in thin film solar cells. Thin films of tin sulphide have been deposited using CBD at three different bath temperatures (27, 35 and 45 0C) onto microscope glass substrates. The X ray diffraction (XRD) analysis of the deposited films reveled that all films has orthorhombic SnS phase as dominant one with preferred orientations along (111) direction. The temperature influence on the crystalline nature and the presence of other phases of SnS has been observed. The average grain size in the films determined from Scherer's formula as well as from Williamson-Hall-plot method agrees well with each other. Energy dispersive X-ray (EDAX) analysis used to determine the film composition suggested that films are almost stoichiometric. The scanning electron microscopy (SEM) reveals that deposited films are pinhole free and consists of uniformly distributed spherical grains. The optical analysis in the 200-1200 nm range suggests that direct allowed transitions are dominant in the absorption process in the films with variation in the band gap (~1.79 to ~2.05 eV) due to variation in deposition temperature. © (2013) Trans Tech Publications, Switzerland.


Patel T.H.,VP and RPTP Science College
Solid State Phenomena | Year: 2014

SnS thin film has been deposited on glass substrate at room temperature using low cost, environmental friendly chemical bath deposition (CBD) technique. The structural parameters of the deposited film have been investigated through X- ray diffraction measurements. The deposited SnS film found almost crystalline with preferred orientations along (111) planes revealing an orthorhombic phase of herzenbergite SnS structure. The lattice parameters and dislocation density were determined. The average grain size estimated to be ~ 25 nm. The surface morphology of the film examined using scanning electron microscopy (SEM) show uniform granular deposition of the film. The energy dispersive analysis of x-rays (EDAX) confirmed stoichiometric deposition. The analysis of the optical absorption spectra of the deposited film in the wavelength range of 200-1200 nm indicate direct allowed transitions as dominant one in the film. The direct band gap determined to be ~ 1.92 eV which is higher than those reported earlier for bulk or single crystal SnS, exhibiting quantum size effect at the observed grain size in the film. This value of band gap is promising for possible use of the deposited film as absorption layer in photovoltaic structures like solar cells. The thermoelectric power measurements indicate p-type electrical conductivity of the deposited films. © (2014) Trans Tech Publications, Switzerland.

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