Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds

TL;DR

This paper applies Landau theory to analyze the pressure-induced phase transition in calcium orthotungstate and related compounds, providing insights into the nature of the transition and its structural characteristics.

Contribution

It demonstrates the use of Landau theory combined with experimental data to characterize the second-order phase transition in scheelite-structured orthotungstates.

Findings

The transition is of second order in nature.

Spontaneous strains effectively describe the phase change.

High-pressure x-ray diffraction supports the theoretical analysis.

Abstract

The pressure-driven tetragonal-to-monoclinic phase transition in CaWO4 and related scheelite-structured orthotungstates is analysed in terms of spontaneous strains. Based upon our previous high-pressure x-ray diffraction results and the Landau theory, it is suggested that the scheelite-to-fergusonite transition is of second order in nature.