High-pressure, High-temperature Synthesis and Properties of the Monoclinic Phase of Y2O3

The monoclinic phase of Y2O3(B-RES) has been synthesized using a Kawai-type multi-anvil apparatus under 20 GPa at 1800 degrees C. Samples of the cubic Y2O3(C-RES) and monoclinic Y2O3 phases were characterized by synchrotron radiation X-ray diffraction, X-ray absorption near edge structure and Raman spectroscopy. Crystal structures of the cubic and monoclinic phases have been examined using Rietveld refinement of the X-ray diffraction data. The cubic-to-monoclinic transition of Y2O3 was reconstructive and irreversible. The X-ray diffraction results were further confirmed by simulation of the X-ray absorption spectra.