PHASE TRANSITIONS IN YTTRIUM OXIDE AT HIGH PRESSURE STUDIED BY RAMAN SPECTROSCOPY

摘要

Raman spectra of Y_2O_3, single crysta1 were recorded at room temperature in a diamond anvil cell up to a pressure of 22 GPa. Two phase transitions were detected at pressures of l2 and l9 GPa. The different phases were identified with the three structures exhibited by rare-earth (RE) sesquioxidest: cubic (C-type), monoclinic (B-type), and rhombohedral (A-type) phases. The first transition corresponds to the C→B transformation and the second transition to the B→A transformation. The reversibility of the two phase transitions as well as the evolution of the Y-O bonds under high pressure is discussed.