Exploring the high-pressure behaviour of polymorphs of AMO4 ternary oxides: crystal structure and physical properties

Abstract

AMO4 ternary oxides are materials of fundamental and technological importance exhibiting a large variety of functional properties. Members of this family of compounds have multiple potential applications; for instance, as scintillators, thermophosphors, photocatalysts, and cathodoluminescence materials. Studies under high-pressure conditions are valuable for understanding the physical properties and phase behaviour of AMO4 oxides. In particular, great progress has been achieved in the last decade towards the understanding of the pressure-effects on the structural, vibrational, and electronic properties of AMO4 materials. Specifically, novel metastable structures with interesting physical properties have been discovered. In this article, a selection of recent results from high-pressure studies on different AMO4 oxides will be discussed, paying particular attention to orthovanadates. Remarkable phenomena like band-gap and volume collapses as well as phonon softening will be discussed and correlated with structural changes. SYNOPSIS The influence of high pressure on the crystal structure of different ternary oxides is discussed giving emphasis to pressure-driven phase transitions and the consequences of structural changes in optical and vibrational properties. Several examples are examined, general conclusions discussed, and possible future directions for the high-pressure study of ternary oxides proposed.