Lattice effects on the formation of oxygen vacancies in perovskite thin films

Abstract

We use first-principles methods to investigate the effects of collective lattice excitations on the formation of oxygen vacancies in perovskite thin films. We find that phonons play a crucial role on the strain-mediated control of defect chemistry at finite temperatures. In particular, zero-temperature oxygen vacancy formation trends deduced as a function of epitaxial strain can be fully reversed near room temperature. Our first-principles calculations evidence a direct link between the lattice contribution to the oxygen vacancy free energy and the volume expansion that the system undergoes when is chemically reduced: The larger the resulting volume expansion, the more favorable thermal excitations are to point defect formation. However, the interplay between the vibrational vacancy entropy, or equivalently, chemical expansion, and epitaxial strain is difficult to generalise as this can be strongly influenced by underlying structural and magnetic transitions. In addition, we find that vacancy ordering can be largely hindered by the thermal lattice excitations.

5 pages, 5 figures

References in corpus (5)

• Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films
• Electrostatic engineering of strained ferroelectric perovskites from first-principles
• Effect of epitaxial strain on cation and anion vacancy formation in MnO
• First-Principles Modeling of Quantum Nuclear Effects and Atomic Interactions in Solid 4He at High Pressure
• Revisiting the zero-temperature phase diagram of stoichiometric SrCoO3 with first-principles methods

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• Growth-Temperature Dependence of Conductivity at the LaCrO${}_3$/SrTiO${}_3$ (001) Interface
• Strain engineering of oxide thin films for photocatalytic applications