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

Abstract

The effect of hydrostatic pressure on structural phase transition temperatures above room temperature in CsPbCl₃ and CsPbBr₃ 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 CsPbCl₃, respectively; 11.3 deg kbar⁻¹ and 12.4 deg kbar⁻¹ for the cubic to tetragonal and the tetragonal to orthorhombic transitions in CsPbBr₃, respectively. It is predicted that the volume contraction makes the R₂₅ modes less stable than the M₃ mode in the cubic phases of CsPbCl₃ and CsPbBr₃.