High-pressure structural investigation of several zircon-type orthovanadates

TL;DR

This study investigates the high-pressure structural behavior of zircon-type EuVO4, LuVO4, and ScVO4 using x-ray diffraction, revealing phase transitions and differences in compressibility among the compounds.

Contribution

It provides new insights into the pressure-induced phase transitions and compressibility of zircon-type orthovanadates, including the first observation of a second transition in EuVO4 and LuVO4.

Findings

EuVO4 and LuVO4 undergo zircon to scheelite transition near 8 GPa

EuVO4 and LuVO4 exhibit a second transition near 21 GPa

ScVO4 is the least compressible among studied orthovanadates

Abstract

Room temperature angle-dispersive x-ray diffraction measurements on zircon-type EuVO4, LuVO4, and ScVO4 were performed up to 27 GPa. In the three compounds we found evidence of a pressure-induced structural phase transformation from zircon to a scheelite-type structure. The onset of the transition is near 8 GPa, but the transition is sluggish and the low- and high-pressure phases coexist in a pressure range of about 10 GPa. In EuVO4 and LuVO4 a second transition to a M-fergusonite-type phase was found near 21 GPa. The equations of state for the zircon and scheelite phases are also determined. Among the three studied compounds, we found that ScVO4 is less compressible than EuVO4 and LuVO4, being the most incompressible orthovanadate studied to date. The sequence of structural transitions and compressibilities are discussed in comparison with other zircon-type oxides.