HIGH-PRESSURE RAMAN-SPECTROSCOPIC STUDY OF LICSSO4 - PRESSURE-INDUCEDPHASE-TRANSITIONS AND AMORPHIZATION

A Raman study of LiCsSO4 as a function of pressure up to 26 GPa has re vealed three distinct first order phase transitions at 2.0, 4.0 and 7. 2 GPa. Above 10 GPa the external modes merge with the background and t he internal modes broaden, suggesting the occurrence of a pressure-ind uced amorphization. The reappearance of external modes and the restora tion of spectral features upon decompression shows a reversible transi tion from the amorphous to a crystalline phase.