Orientation control of oxygen vacancy channel (OVC) is a highly desirable for tailoring oxygen diffusion as it serves fast transport channel in ion conductors, which is widespread exploited in solid-state fuel cells, catalysts, and ion-batteries. Direct observation of oxygen-ions hopping towards preferential vacant sites is a key to clarifying migration pathways. Here we report the anisotropic oxygen-ion migration mediated by strain in ultrathin cobaltites via in-situ thermal activation in an atomic-resolved transmission electron microscopy. Oxygen migration pathways are constructed on the basis of the atomic structure during the OVC switching, which is manifested as the vertical-to-horizontal OVC switching under tensile strain, but the horizontal-to-diagonal switching under compression. We evaluate the topotactic structural changes to OVC, determine the crucial role of tolerance factor for OVC stability and establish the strain-dependent phase diagram. Our work provides a practical guide for engineering OVC orientation that is applicable ionic-oxide electronics.
@article{arxiv.2111.10565,
title = {Dynamics of anisotropic oxygen-ion migration in strained cobaltites},
author = {Qinghua Zhang and Fanqi Meng and Ang Gao and Xinyan Li and Qiao Jin and Shan Lin and Shengru Chen and Tongtong Shang and Xing Zhang and Haizhong Guo and Can Wang and Kui-juan Jin and Xuefeng Wang and Dong Su and Lin Gu and Er-Jia Guo},
journal= {arXiv preprint arXiv:2111.10565},
year = {2022}
}