High pressure phase transition in samarium monochalcogenides SmX (X = S, Se, Te) and their alloy SmS1−xSex

•We have investigated the high pressure structural phase transition of SmS and its SmS1−xSex alloy.•A modified model IIPM (including the polarizability effect) has been developed.•Phase transition pressures are associated with a sudden collapse in volume.•Our model is able to explain Cauchy violations.•We have extended our study to elastic and mechanical properties of SmX (X = S, Se, Te).

Phase transition pressures, relative volume changes, elastic and thermophysical properties of Samarium monochalcogenides SmX (X = S, Se, Te) have been studied. An improved interaction potential model has been developed which includes Coulomb, three-body interaction, polarizability effect and overlap repulsive interaction operative up to second neighbor ions. In addition, we have investigated the phase transition pressure and associated volume collapse in SmS1−xSex alloy (0 ⩽ x ⩽ 1) which shows transition from discontinuous to continuous as x is reduces. The present results are in general in good agreement with experimental data available for the end point members (x = 0 and x = 1). The results for the alloy counter parts are also in fair agreement with experimental data generated from the vegard’s law.

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