Study of phase transition of HoVO4 under high pressure by Raman scattering and ab initio calculations

Abstract

The aim of this work is to confirm that the HoVO4 has a zircon-to-scheelite phase transition as reported in ScVO4 and YVO4. Firstly, we prepare HoVO4 samples used in the experiments by solid state reaction of appropriate quantities of pre-dried Ho2O3 and V2O5. And the Raman spectra of HoVO4 are measured in a pressure range from ambient pressure to 21.25 GPa at room temperature by using a diamond anvil cell. The discontinuities on Raman mode shifts and the occurrence of new Raman bands provide strong evidence for a phase transition at 9.3 GPa. Secondly, ab initio calculations are performed and the results reveal a zircon-type (I41/amd) to scheelite-type (I41/a) structure in this phase transition. The results are compared with those previously reported for the relevant ScVO4 and YVO4 with a common zircon-to-scheelite phase transition, mainly duo to volume collapses. The results in this work may improve our understanding of the high phase and structure of HoVO4 and benefit the application of this material.