Raman spectroscopic study of pressure–induced phase transitions in tridymite modifications

Abstract

Pressure–induced phase transitions of tridymite modifications (MC, MX–1, and PO–10) were investigated by in–situ Raman spectroscopy. Starting from MC, a transition to PO–10 was observed at 0.4 GPa. At about 1.6 GPa, new Raman peaks appeared and were observed up to 8.7 GPa. This revealed a new phase, and it reverted to PO–10 at around 0.4 GPa during decompression. Contrary to previous study, PO–10 was recovered to ambient pressure. MX–1 also transformed to PO–10, and PO–10 was recovered. Starting from PO–10, the transition to the new phase was also observed but was gradual and the phase reverted to PO–10 during decompression. Present study revealed a new route to form PO–10 from MC and suggests rare PO–10 found in meteorites could be formed through this route.