High-Pressure Structural Phase Transition in Mg<sub>x</sub>Cd<sub>1-x</sub>O Compounds

Abstract

The high-pressure technique is useful to understand physical properties because the technique can directly control bond length and phase transition. As a general trend, the pressure-induced phase transition causes an increase of coordination number with a drastic change of their physical properties. Here, we attempt to explore the pressure-induced phase transitions from the sixfold-coordinated NaCl structure (B1) to the eightfold-coordinated CsCl structure (B2) in MgxCd1−xO by applying an effective interionic interaction potential, which includes the long range Coulomb, van der Waals (vdW) interaction and the short-range repulsive interaction upto second-neighbor ions within the Hafemeister and Flygare approach. Assuming that both the ions are polarizable, the Slater-Kirkwood variational method is employed to estimate the vdW coefficients for parent compounds. The estimated values of the phase transition pressure (Pt) increase with Mg concentration. The vast volume discontinuity in pressure volume phase diagram identifies the structural phase transition from B1 to B2 structure. The results obtain from the present calculations requires the complete understanding of many physical interactions that are essential to ternary oxides, containing elements with size and chemical mismatch, will lead to a consistent explanation of the documented structural properties.