Stability of the tetragonal phase of BaZrO3 under high pressure

TL;DR

This study combines experimental and computational methods to analyze the high-pressure phase stability of BaZrO3, confirming the cubic-to-tetragonal transition at 10 GPa and ruling out further phase transitions up to 45 GPa.

Contribution

It provides a comprehensive re-investigation of BaZrO3's phase stability under pressure, clarifying previous conflicting reports and demonstrating the stability of the tetragonal phase at high pressures.

Findings

Cubic-to-tetragonal transition confirmed at 10 GPa

No additional phase transitions observed up to 45 GPa

Tetragonal phase becomes more stable with increasing pressure

Abstract

In this paper, we revisit the high-pressure behavior of BaZrO3 by a combination of first-principle calculations, Raman spectroscopy, and x-ray diffraction under high pressure. We confirm experimentally the cubic-to-tetragonal transition at 10 GPa and find no evidence for any other phase transition up to 45 GPa, the highest pressures investigated, at variance with past reports. We re-investigate phase stability with density functional theory considering not only the known tetragonal (I4/mcm) phase but also other potential antiferrodistortive candidates. This shows that the tetragonal phase becomes progressively more stable upon increasing pressure as compared to phases with more complex tilt systems. The possibility for a second transition to another tilted phase at higher pressures, and in particular to the very common orthorhombic Pnma structure, is therefore ruled out.