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In this work, the structural, electronic, mechanical, optical, thermophysical and phonon properties of TaFeSb are investigated using density functional theory in stable cubic state. On the basis of elastic properties reported, it is confirmed that this compound shows hardness (due to high bulk modulus), is ductile and has anisotropic nature. The band structure and density of states calculations of TaFeSb exhibit semiconducting nature. Various optical properties viz. high absorption and low reflectivity are calculated, which confirm its applications in optoelectronics. The thermophysical properties of TaFeSb at high temperatures and high pressures are studied for the first time, which can pave new directions to thermoelectric applications at high temperatures and high pressures. It is found that TaFeSb follows Debye T3 law and Dulong–Petit limit at elevated temperatures and pressures. Moreover, we have done detailed analysis on phonon dispersion relation, density of phonon states and thermal properties of TaFeSb, which would help in heat dissipation in computer chips and thermoelectric devices. [ABSTRACT FROM AUTHOR]

In present work we have studied half-Heusler compound NiTiSn in perspective of optical, mechanical and thermophysical properties at high temperature and high pressure using density functional theory. We have calculated various dielectric properties viz absorption coefficients, optical conductivity, optical reflectivity and electron energy loss. We have also found high refractive index n(0) ≈ 5 of NiTiSn indicating highly denser medium for low energy waves. The calculated absorption coefficient and optical conductivity are in agreement with the experimental ones for optical device. The optical investigation of the compound shows high reflectivity in the UV region of the photon energy. The elastic properties are investigated in most stable structure of NiTiSn in order to ensure its mechanical applications. Our estimated values of Poisson ratio (n = 0.2735) and pughratio (B/G = 1.87) confirm the metallic nature of NiTiSn. Various thermophysical properties viz. Debye temperature, isothermal coefficients, heat capacity, entropy and volume have been studied at high temperature and high pressures which will upgrade its thermoelectric properties study. The thermophysical properties ensures the Debye T3 law and Dulong Petit limit of NiTiSn at high temperatures and high pressures. [ABSTRACT FROM AUTHOR]

To study phase transition and elastic properties at high pressures and high temperatures, we have developed a realistic interaction potential model (RIPZpe) including temperature effects. This model is completely suitable for explaining the inter-atomic interaction involved at high temperature and high pressure as it includes the three-body interaction (TBI) and zero point energy effects. The phase transition of KBr crystal at high pressure and high temperatures including the TBI is done for the first time. We have estimated the phase transition pressures, volume collapses and elastic behaviour at various high pressure and high temperatures by RIPZpe approach and the results found are well suited with available experimental data. [ABSTRACT FROM AUTHOR]

A realistic interaction potential model approach by including temperature effects is developed to study phase transition, elastic properties and thermo-physical properties at very high pressures and temperatures. This approach is effectively able to explain the inter-atomic interaction involved at high temperature and high pressure as it includes the three-body interactions. Earlier works overlooked the three-body interactions at high temperature and pressures. Moreover, the phase-transition pressures of MgO crystal at high temperatures including the three-body interaction are computed for the first time. Elastic behavior, anisotropic factor and Debye temperature of MgO at high pressures and temperatures are also reported. [ABSTRACT FROM AUTHOR]

A theoretical analysis of pressure induced phase transition of actinide monoarsenides having NaC1-type (B1) structure using realistic three body interaction potential model (RTBIPM) for Np, Pu, Th and U is presented. Present RTBIPM model parametrically includes different parameters separately for different phases which other theoretical workers ignore it. The phase transition pressures and elastic behavior of these actinide monoarsenides are found closer to the experimental results. A static simulation technique including three body interaction effects has been used to calculate the equation of state, pressure derivatives of elastic constants and their stability criterion. The important finding of the present study is the effect of high pressure on the three-body interaction effect at the structural phase transition pressure. Further, by using different parameters separately in the RTBIPM for different phases makes it realistic approach for high pressure studies. [ABSTRACT FROM AUTHOR]

The high pressure phase transition and elastic behavior of rare earth monoselenides (CeSe, EuSe and LaSe) which crystallize in a NaCl-structure have been investigated using the three body interaction potential (TBIP) approach. These interactions arise due to the electronshell deformation of the overlapping ions in crystals. The TBP model consists of a long range Coulomb, three body interactions and the short range overlap repulsive forces operative up to the second neighboring ions. The authors of this paper estimated the values of the phase transition pressure and the associated volume collapse to be closer than other calculations. Thus, the TBIP approach also promises to predict the phase transition pressure and pressure variations of elastic constants of lanthanide compounds. [ABSTRACT FROM AUTHOR]