Pressure-induced phase transition in cubic Lu2O3

Abstract

The phase transition in cubic Lu2O3 has been investigated by angle dispersive x-ray diffraction and Raman scattering in a diamond anvil cell up to 46.8 GPa and 40.2 GPa, respectively. The diffraction data indicated that a phase transition from the cubic to a monoclinic structure started at 12.7 GPa and completed at 18.2 GPa. This high pressure monoclinic phase is stable up to at least 46.8 GPa and can be quenched to ambient conditions. This irreversible cubic to monoclinic structural transformation has also been confirmed by Raman scattering measurements. A third-order Birch–Murnaghan fit based on the observed pressure-volume data yields a zero pressure bulk modulus of B0=214(6) GPa, its pressure derivative B0′=9(1) for the low-pressure cubic phase; and B0=218(13) GPa, B0′=2.3(3) for the high pressure monoclinic phase, respectively. The mode Grüneisen parameters of different Raman modes for both cubic and monoclinic phases have also been determined.