Experimental and theoretical study of structural properties and phase transitions in YAsO4 and YCrO4

TL;DR

This study combines experimental X-ray diffraction and theoretical calculations to analyze pressure-induced structural phase transitions in YAsO4 and YCrO4, revealing a sequence of structural changes and their properties.

Contribution

It provides a comprehensive characterization of phase transitions in YAsO4 and YCrO4 under high pressure using combined experimental and theoretical methods, including new structural sequences.

Findings

Identified zircon to scheelite phase transition in both compounds.

Proposed a zircon  scheelite  SrUO4-type sequence for YAsO4.

Reported band gaps and lattice-dynamics properties.

Abstract

We have performed experimental and theoretical studies of the structural stability of YAsO4 and YCrO4 at high pressures. X-ray diffraction experiments together with ab initio total-energy and lattice-dynamics calculations have allowed us to completely characterize a pressure-induced structural phase transition from the zircon to the scheelite structure in both compounds. Furthermore, total-energy calculations have been performed to check the relative stabilities of different candidate structures at different pressures and allow us to propose for YAsO4 the zircon \rightarrow scheelite \rightarrow SrUO4-type sequence of structures. In this sequence, sixfold arsenic coordination is attained for the SrUO4-type structure above 32 GPa. The whole sequence of transitions is discussed in comparison with YVO4, YPO4, YNbO4, YMoO4, and YTaO4. Also a comparative discussion of lattice-dynamics properties is presented. The band-gap for YAsO4 and YCrO4 and band structure for YAsO4 are also reported. Finally, the room-temperature equation of state of different compounds is also obtained.