Pressure-induced phase transformations in cubic Gd2O3

Abstract

High-pressure transformation and compression behavior of Gd2O3 were investigated using synchrotron radiation x-ray diffraction in a diamond anvil cell up to 44 GPa at room temperature. The structural transformation from a cubic to a monoclinic phase occurred during the sample precompression process. Phase transitions from both the cubic and the monoclinic polymorphs to a hexagonal structure were observed. The hexagonal phase was stable up to the highest pressure in this study and was not quenchable and transformed to a monoclinic phase after pressure release. The bulk moduli of Gd2O3 for the cubic, monoclinic, and hexagonal phases were obtained by fitting the compression data to the Birch–Murnaghan equation of state. Moreover, an anomaly of the hexagonal type Gd2O3 was observed.