Effect of pressure on the order-disorder phase transitions of B cations in AB'_1/2B''_1/2O₃ perovskites

Perovskite-like oxides AB'_1/2B''_1/2O₃ may experience different degrees of ordering of the B cations that can be varied by suitable synthesis conditions or post-synthesis treatment. In this work the earlier proposed statistical model of order-disorder phase transitions of B cations is extended to account for the effect of pressure. Depending on the composition, pressure is found to either increase or decrease the order-disorder phase transition temperature. The change in transition temperature due to pressure in many cases reaches several hundred kelvin at pressures accessible in the laboratory, which may significantly change the degree of atomic ordering. The work is intended to help in determining how pressure influences the degree of atomic ordering and to stimulate research into the effect of pressure on atomic order-disorder phase transitions in perovskites.