STUDIES ON CSBR WITH SYNCHROTRON-RADIATION UNDER ULTRAHIGH PRESSURE UP TO 115 GPA

In situ high pressure energy dispersive x-ray diffraction experiments have been carried out on CsBr by using diamond anvil cell device with synchrotron radiation source. The maximum pressure is 115 GPa. The str ucture of CsBr is changed from simple cubic phase to tetragonal phase at pressure about 53 GPa, marked by the splitting of its strongest dif fraction line (110). At pressure above 98 GPa, the color change of CsB r from transparent to red-brown was observed. No pressure-induced tran sition from insulator to metal is found at higher pressure up to 115 G Pa.