Credit: Reprinted figure with permission from Advanced Functional Materials. Copyright 2016 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Stretching or compressing a material allows tailoring the concentration of missing oxygen atoms that directly affects magnetic, electronic, and catalytic properties. The schematic shows stretching (blue arrows) of a thin film (red atoms with green octahedra). The stretching decreases the stability of oxygen in the crystalline structure, allowing oxygen atoms to move more freely through channels (yellow). This creates more missing oxygen atoms in the crystalline structure. These missing atoms are defects called vacancies. In contrast, compression stabilizes the oxygen atoms and prevents the formation of these vacancies.