Purvee Bhardwaj

Structural and elastic properties of barium chalcogenides (BaX, X=O, Se, Te) under high pressure

In the present paper we have investigated the high-pressure, structural phase transition of Barium chalcogenides (BaO, BaSe and BaTe) using a three-body interaction potential (MTBIP) approach, modified by incorporating covalency effects. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from TBIP show a reasonably good agreement with experimental data. Here, the transition pressure, NaCl-CsCl structure increases with decreasing cation-to-anion radii ratio. In addition, the elastic constants and their combinations with pressure are also reported. It is found that TBP incorporating a covalency effect may predict the phase transition pressure, the elastic constants and the pressure derivatives of other chalcogenides as well.

Pressure induced structural phase transitions—A review

AbstractThe contemporary status of experimental as well as theoretical advances within the special view of structural phase transitions is reviewed. A brief outline of phase transitions and its classification is presented first. High-pressure experimental techniques developed for studying the structural phase transitions and elastic properties are reviewed. The complete set of theoretical and experimental data obtained is for the group II–IV alkaline earth chalcogenides. Here the authors review the currently used calculations and high-pressure behavior of these materials and the theoretical work that has been done on them.

Numerical analysis of LaBi at high temperature and pressure

Abstract In this paper we focused on the structural, elastic and thermodynamic properties of the B1 phase of LaBi by using the modified TBP model, including the role of temperature. We successfully obtained the phase transition pressure and volume change at different temperatures. In addition, elastic constants and bulk modulus of B1 phase of LaBi at different temperatures were discussed. Our results were comparable with the previous ones at high temperatures and pressures. The thermodynamical properties of the B1 phase of LaBi were also predicted.

Role of temperature in the numerical analysis of CaO under high pressure

In this paper we focus on the elastic and thermodynamic properties of the B1 phase of CaO by using the modified TBP model, including the role of temperature. We have successfully obtained the phase transition pressure and volume change at different temperatures. In addition elastic constants and bulk modulus of B1 phase of CaO at different temperatures are discussed. Our results are comparable with the previous ones at high temperatures and pressures. The thermodynamical properties of the B1 phase of CaO are also predicted.

Phase transition and bulk properties of some polonide compounds: a comparative study

In the present paper the structural and electronic properties of polonides of lead, barium and calcium polonide (PbPo, BaPo and CaPo) have been reported. These properties have been studied using first principles calculations as well as the interionic potential model modified with the covalency effect. Gibbs free energy and enthalpy calculations show that these compounds undergo a structural phase transition from NaCl-type structure to CsCl-type structure. The electronic band structure and density of states of the PbPo, BaPo and CaPo have also been reported. The calculated equilibrium structural parameters are in good agreement with the available experimental results.

Phase transition, structural, mechanical and thermal properties of erbium pnictides under pressure

In this article, we have investigated the high-pressure structural phase transition of erbium pnictides (ErX; X = N, P and As). An extended interaction potential model has been developed (including the zero-point energy effect in three-body interaction potential model). Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses have been predicted successfully. The elastic constants, their combinations and pressure derivatives are also reported. The pressure behaviour of elastic constants, bulk modulus and shear modulus have been presented and discussed. Moreover, the thermophysical properties such as molecular force constant (f), infrared absorption frequency (υ 0), Debye temperature (θ D) and Grunneisen parameter (γ) have also been predicted.

Structural properties of TiN and TiO at high temperature and pressure

In this paper we have developed an effective interaction potential model to study the high pressure phase transition of transition metal compounds TiX (X=N,O), having B1 structure at room temperature. We have theoretically investigated phase transition pressures and volume collapses including the temperature effect, and found results well suited with available experimental data. The elastic constants are also reported. The inclusion of temperature effect in TBIP makes the present model suitable for theoretical high-pressure studies.

High pressure phase transition and elastic properties of covalent heavy rare-earth Antimonides

AbstractIn the present paper, we report an investigation into the high-pressure structural phase transition of rare earth antimonides (DySb and ErSb). A modified interaction potential model (MIPM) (including the covalency effect) has been developed. Phase transition pressures are associated with a sudden collapse in volume, indicating the occurrence of a first order phase transition. At compressed volumes, these compounds are found in the CsCl phase. The phase transition pressures and associated volume collapses obtained from the potential model developed here show a generally better agreement with available experimental data than others available in the literature. The elastic constants and bulk modulus are also reported. Our results are, in general, in good agreement with experimental and theoretical data where available, and provide predictions where data are unavailable. FigureVariation of Gibb’s free energy with

First principle calculation of structural, electronic and elastic properties of rare earth nitride

Abstract First principle calculation of the electronic and elastic properties of CeN nitride, which crystallizes in the rock-salt structure, is reported in the present paper. The ground state properties, such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B′) are reported. These results show good agreement with the experimental and other theoretical results. Besides, we have studied the Murnaghan’s equation of state, and used it to fit the theoretical electronic ground state energy and obtain thermodynamic quantities such as the bulk modulus. Furthermore the electronic band structure, total density of states and partial density of states of CeN are also discussed.

Structural Analysis of Rare Earth Compound with NaCl-Structure

The structural properties of rare earth compound in NaCl-structure are studied in the present investigation. To study these properties of erbium telluride (ErTe), the Realistic Interaction Potential Approach (RIPA) model has been used. Present compound shows NaCl-type to CsCl-type structural phase transformation. The structural properties, including phase transition pressure and volume collapse are obtained and compared with available literature. The calculated equilibrium structural parameters are in good agreement with the available experimental and theoretical results. Further more to study the electronic properties, band structure and density of state are reported.