Structural investigation of LaAlO3 up to 63 GPa

TL;DR

This study uses high-pressure synchrotron x-ray diffraction to investigate LaAlO3, confirming a rhombohedral to cubic phase transition at 14.8 GPa and analyzing its structural evolution up to 63 GPa.

Contribution

It provides detailed high-pressure structural data for LaAlO3, confirming phase transition behavior and the evolution of distortions in perovskites under pressure.

Findings

Rhombohedral to cubic transition at 14.8 GPa

Crystal remains cubic up to 63 GPa

Pressure dependence of superstructure reflections

Abstract

We report a high-pressure single-crystal synchrotron x-ray diffraction on a LaAlO3 single crystal. The transition from rhombohedral to cubic at 14.8 GPa is confirmed by the loss of the superstructure reflections, whose intensity shows a linear pressure dependence, characteristic of a second-order transition. The crystal remains cubic up to 63 GPa, the highest pressure reached, which provides a confirmation over a very large pressure range of the general rules for the evolution of distortions of perovskites under pressure. We give the parameters of Birch-Murnaghan equations of state in the low- and high-pressure phases and discuss the evolution of the bulk modulus.