High-Temperature Structural Phase Transition of K2SO4 and K2SeO4 Crystals Studied by X-Ray Diffraction

Abstract

High-temperature structural phase transitions in K2SO4 and K2SeO4 crystals have been studied by X-ray diffraction. Laue and precession photographs were taken with Mo radiation at several high temperatures. Results indicate that the symmetry of both crystals changes from the orthorhombic to the hexagonal system through structural phase transition. Possible space groups are P63/mmc, P 63mc, or P6̄c from extinction conditions in the high-temperature phases. The crystal structure of K2SeO4 is preliminarily assumed to be isostructural with K2SO4 in the high-temperature phase. Further studies of the crystal structure and the phase transitions of K2SeO4 are required.