Phase transition properties of SmTe under pressure

Abstract

Phase transition properties of SmTe under high pressure have been investigated through ab initio pseudo-potential calculations within the framework of density functional theory. Local density approximation based on exchange-correlation energy optimization has been used for calculating the total energy of the system. The calculated equilibrium lattice constant, bulk modulus and its pressure derivative agree well with the experimental data. The first-principles studies of isostructural valence transition from Sm²⁺ to Sm³⁺ in B1 phase () and from B1 → B2 phase transition characterized by the space group in bulk SmTe have been carried out. The calculated transition pressure, equation of state and volume collapse show good agreement with experimental results. Under ambient conditions, the energy of Sm²⁺ in B1 phase is found to be lower than that of Sm³⁺. At high pressures beyond B1 → B2 phase transition, the energy of B2 phase is found to be slightly lower than that in B1 phase.

Keywords:

• high-pressure phase transition
• SmTe
• equation of state
• structural phase transition

Acknowledgements

The authors are thankful to the University Grants Commission, New Delhi for financial support. S. Kulshrestha is also thankful to UGC, New Delhi for the award of fellowship. Thanks are also due to SIESTA team for providing permission to use the code.