Investigation of Phase Transitions of ZrO2 under High-Pressure and High-Temperature Conditions by Raman Spectroscopy

Using argon as a pressure medium, the phase transitions of monoclinicstructured ZrO2 under high-pressure and high-temperature have been investigated by means of in situ Raman spectra method and a laser-heated diamond anvil cell (DAC). At room temperature, the baddeleyite-type ZrO2 begins to transform to a new phase at 3.4 GPa, Raman bands from the new phase become prominent at 10.4 GPa, and this new high-pressure structure retains up to 15.3 GPa, the highest pressure before heated. The new phase has been identified as Pbca phase. Raman spectrum of Pbca phase is presented for the first time based on our experiments. At pressure of 15.3 GPa the Pbca phase was heated by YAG laser to about 1 000~1 500 ℃, and then it transforms to a PbCl2 phase. This phase is stable up to 23 GPa, the highest pressure in this study.