Effects of pressure on the local atomic structure of CaWO4 and YLiF4: Mechanism of the scheelite-to-wolframite and scheelite-to-fergusonite transitions

TL;DR

This paper investigates how pressure affects the atomic structure of CaWO4 and YLiF4, elucidating the mechanisms behind their phase transitions from scheelite to wolframite or fergusonite, and explores transition pressures across related compounds.

Contribution

It provides a detailed analysis of pressure-induced phase transition mechanisms in scheelite compounds and correlates transition pressures with structural packing ratios.

Findings

Pressure influences axial parameters via interatomic bond changes.

Transition mechanisms involve specific atomic rearrangements.

Transition pressure correlates with packing ratios of BX4 units.

Abstract

The pressure response of the scheelite phase of CaWO4 (YLiF4) and the occurrence of the pressure induced scheelite-to-wolframite (M-fergusonite) transition are reviewed and discussed. It is shown that the change of the axial parameters under compression is related with the different pressure dependence of the W-O (Li-F) and Ca-O (Y-F) interatomic bonds. Phase transition mechanisms for both compounds are proposed. Furthermore, a systematic study of the phase transition in 16 different scheelite ABX4 compounds indicates that the transition pressure increases as the packing ratio of the anionic BX4 units around the A cations increases.