High pressure phase transition and elastic behavior of europium monochalcogenides

• An improved interaction potential (IIPM) model with polarizability has been applied for the first time in EuX (X=O, S, Se, and Te).
• This model has been applied to study structural and elastic behavior of EuX.
• P–V curves show that EuX undergo NaCl to CsCl type structural transition.
• Anharmonic properties have been investigated for the first time in EuX.

A study of high-pressure phase transition and elastic properties of europium monochalcogenides with NaCl structure has been carried out in this paper using improved interaction potential model (IIPM). This model incorporates long-range Coulomb effect, three body interaction, polarization effect and short range repulsive interaction extended up to next nearest neighbors. These compounds exhibit first order structural phase transition from B1 (NaCl) to B2 (CsCl) structure at pressures 39.3, 21.1, 14.4 and 11.6 GPa with sudden collapses in volume 10.76%, 11.35%, 13.34% and 12.12% respectively for EuO, EuS, EuSe and EuTe. The results obtained from present potential model show a generally good agreement with available experimental data. The elastic constants, their combinations and pressure derivatives are also reported. Thermodynamical properties like the ratio of thermal expansion coefficient to specific heat (αv/Cv), Gruneisen parameter are also studied.

Variation of Gibbs free energy difference with pressure for EuX (=O, S, Se, and Te).Figure optionsDownload as PowerPoint slide