Investigation of the phase stability ofLuVO4 at high pressure using powder x-ray diffraction measurements and lattice dynamicalcalculations

Abstract

High pressure angle dispersive x-ray diffraction measurements are carried out onLuVO4 in adiamond anvil cell up to 33 GPa at the Elettra synchrotron radiation source. The measurements showthat LuVO4 undergoes a zircon to scheelite structure phase transition with a volume change of about11% at about 8 GPa. A second transition to a monoclinic fergusonite structure occurs above16 GPa. The data are also recorded while releasing the pressure, and indicate that thescheelite phase is metastable under ambient conditions. The equations of stateand changes in internal structural parameters are reported for various phases ofLuVO4. Lattice dynamical calculations based on a transferable interatomic potential were alsoperformed and the results support the stability of the scheelite structure at high pressures.The calculated structure, equation of state and bulk modulus for all the phases are in fairagreement with the experimental observations.