High Pressure phase transitions in BaWO4

TL;DR

This study investigates high-pressure phase transitions in BaWO4 using in-situ x-ray diffraction, revealing a transition from scheelite to possibly fergusonite around 7 GPa and a further transition to a disordered phase above 14 GPa, with both being reversible.

Contribution

The paper provides new experimental evidence on the high-pressure phases of BaWO4, clarifying the nature of the phase transitions and proposing a different phase assignment than previous Raman studies.

Findings

BaWO4 transitions from scheelite to a possible fergusonite phase at ~7 GPa.

A second transition to a disordered phase occurs above 14 GPa.

Both phase transitions are reversible under pressure.

Abstract

Using in-situ angle dispersive x-ray diffraction, we have shown that barium tungstate, which exists in scheelite phase at ambient conditions, transforms to a new phase about seven giga pascal. Analysis of our data based on Le bail refinement suggests that this phase could be fergusonite and not mercuric molybdate type, which was proposed earlier from the Raman investigations. Beyond fourteen giga pascal this compound undergoes another phase transformation to a significantly disordered structure. Both the phase transitions are found to be reversible.