Effect of Hydrostatic Pressure on the Structural Phase Transitions in CsPbCl3 and CsPbBr3

The effect of hydrostatic pressure on structural phase transition temperatures above room temperature in CsPbCl 3 and CsPbBr 3 was studied by dielectric measurements at high pressures up to about 8 kbar. The initial pressure coefficients of the transition temperatures are 7.65 deg kbar -1 , 5.2 deg kbar -1 , and 5.4 deg kbar -1 for the cubic to tetragonal, the tetragonal to orthorhombic, and the orthorhombic to monoclinic transitions in CsPbCl 3 , respectively; 11.3 deg kbar -1 and 12.4 deg kbar -1 for the cubic to tetragonal and the tetragonal to orthorhombic transitions in CsPbBr 3 , respectively. It is predicted that the volume contraction makes the R 25 modes less stable than the M 3 mode in the cubic phases of CsPbCl 3 and CsPbBr 3 .