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Singh A.,Sadhu Vaswani College | Singh A.,Barkatullah University | Srivastava V.,Barkatullah University | Srivastava V.,NRI Institute of Research and Technology | And 2 more authors.
Journal of Nuclear Materials | Year: 2010

We report an ab initio calculation of pressure-induced structural phase transition and electronic properties of the NaCl-type Cm-based pnictides namely CmX (X = N, P, As, Sb and Bi). The total energy as a function of volume is obtained by means of self-consistent tight-binding linear muffin tin orbital (TB-LMTO) method by performing spin and non-spin polarized calculation. Magnetically the CmX compounds are stable in ferromagnetic (FM) state and their crystal structure is NaCl-type at ambient condition. From the present study, we predict a structural phase transition from ferromagnetic (FM) NaCl-type (B 1 phase) structure to ferromagnetic CsCl-type (B 2 phase) structure for curium pnictides in the pressure range of 51.0-10.0 GPa (CmN to CmBi). The pressure-induced transition is found to be first order. The band structure and density of states (DOS) are plotted in FM-B 1 phase and FM-B2 phase. Apart from this the groundstate properties like magnetic moment, lattice parameter and bulk modulus are calculated and compared with the available theoretical and experimental results. © 2010 Elsevier B.V. All rights reserved. Source


Srivastava V.,NRI Institute of Research and Technology | Srivastava V.,Barkatullah University | Khan A.A.,Sagar Institute of Science and Technology and Engineering | Rajagopalan M.,Anna University | And 2 more authors.
Physica B: Condensed Matter | Year: 2012

Ab initio calculation on B2-cadmium rare earth (RE), CdRE (RE=La, Ce and Pr) intermetallics has been performed at T=0 K with respect to their structural, electronic and thermal properties. The structural and electronic properties are derived using self-consistent tight binding linear muffin tin orbital method at ambient and at high pressure. Other properties like lattice parameter, bulk modulus, density of states, electronic specific heat coefficient, cohesive energy, heat of formation, Debye temperature and Grüneisen constant for CdRE are also estimated. The REf effect can be seen in CdPr in terms of variation in the density of states and opens a possibility of structural instability. A pressure induced variation of Debye temperature is also presented for three cadmium rare earth intermetallics. © 2011 PublishedbyElsevierB. V.Allrightsreserved. Source


Pagare G.,P.A. College | Srivastava V.,NRI Institute of Research and Technology | Sanyal S.P.,Barkatullah University | Rajagopalan M.,Anna University
Physica B: Condensed Matter | Year: 2011

The ground state electronic structure and thermal properties of B 2-type intermetallic compounds AlRE (RE: Pm, Sm, Eu, Tb, Gd and Dy) have been studied using a self-consistent tight-binding linear muffin-tin orbital (TB-LMTO) method at ambient as well as at high pressure. These compounds show metallic behavior under ambient condition. The band structure, total energy, density of states and ground state properties like lattice parameter, bulk modulus are calculated in the present work. The DebyeGrneisen model is used to calculate the Debye temperature and the Grneisen constant. The calculated results are in good agreement with the reported experimental and other theoretical results. The variation in the Debye temperature with pressure has also been reported. We present a detailed analysis of the role of f electrons of RE in the AlRE system. © 2010 Elsevier B.V. All rights reserved. Source


Bhajanker S.,NRI Institute of Research and Technology | Bhajanker S.,Barkatullah University | Srivastava V.,NRI Institute of Research and Technology | Srivastava V.,Barkatullah University | And 2 more authors.
Journal of Physics: Conference Series | Year: 2012

The mechanical and thermal properties of praseodymium monochalcogenides and monopnictides are calculated using elastic constants, those have been derived from two body inter- ionic potential theory. We have calculated the Young's modulus (E), Poisson's ratio (v), anisotropy factors (A), sound velocities and Debye temperature (θ D) for these compounds. The bulk modulus to shear modulus ratio (B/G) lies between 1.75-1.92 for all these compounds, which shows that all compounds are ductile in nature. Young's modulus shows that PrS and PrAs are stiffer than the other monochalcogenides and monopnictides of praseodymium. The variation of elastic constants (C 11, C 44) with pressure and the variation of Debye temperature with pressure are also presented for these compounds. Source


Singh A.,Sadhu Vaswani College | Singh A.,Barkatullah University | Srivastava V.,Barkatullah University | Srivastava V.,NRI Institute of Research and Technology | And 2 more authors.
Physica B: Condensed Matter | Year: 2010

We report ab initio calculations of pressure-induced structural phase transition and electronic properties of the NaCl-type actinide nitrides namely AnN (An=Np and Cm). The total energy as a function of volume is obtained using the self-consistent tight-binding linear muffin tin orbital (TB-LMTO) method by performing spin and non-spin-polarized calculations. Magnetically the AnN compounds are stable in ferromagnetic (FM) state at ambient condition. From the present study, we predict a structural phase transition from ferromagnetic (FM) NaCl-type (B1 phase) structure to ferromagnetic CsCl-type (B2 phase) structure for these in the pressure range of 80.0-50.0 GPa. The pressure-induced transition is found to be first order. The band structure and density of states (DOS) are reported in both FM-B1 phase and FM-B2 phase. The ground-state properties such as magnetic moment, lattice parameter and bulk modulus are calculated and compared with the available theoretical and experimental results. © 2010 Elsevier B.V. All rights reserved. Source

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