Exploring the High-Temperature Stabilization of Cubic Zirconia from Anharmonic Lattice Dynamics

Kasper Tolborg, Aron Walsh

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Finite-temperature stability of crystals is of continuous relevance in solid-state chemistry with many important properties only emerging in high-temperature polymorphs. Currently, the discovery of new phases is largely serendipitous due to a lack of computational methods to predict crystal stability with temperature. Conventional methods use harmonic phonon theory, but this breaks down when imaginary phonon modes are present. Anharmonic phonon methods are required to describe dynamically stabilized phases. We investigate the high-temperature tetragonal-to-cubic phase transition of ZrO2 based on first-principles anharmonic lattice dynamics and molecular dynamics simulations as an archetypical example of a phase transition involving a soft phonon mode. Anharmonic lattice dynamics calculations and free energy analysis suggest that the stability of cubic zirconia cannot be attributed solely to anharmonic stabilization and is thus absent for the pristine crystal. Instead, an additional entropic stabilization is suggested to arise from spontaneous defect formation, which is also responsible for superionic conductivity at elevated temperatures.

Original languageEnglish
Pages (from-to)3314-3319
Number of pages6
JournalCrystal Growth and Design
Volume23
Issue number5
DOIs
StatePublished - 3 May 2023

Bibliographical note

Funding Information:
We thank A. K. Cheetham for suggesting this problem, T. Tadano for assistance with the ALAMODE package, and M. W. Finnis for fruitful discussions. K.T. acknowledges the Independent Research Fund Denmark for funding through the International Postdoctoral grant (0164-00015B). Via our membership of the UK’s HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER2 UK National Supercomputing Service ( http://www.archer2.ac.uk ).

Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.

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