Colossal Ionic Conductivity in Interphase Strain-Engineered Nanocomposite Films
Chuanrui Huo, Kun Xu, Liyang Ma, Tianyu Li, Hao Li, Xiaoyan Yang, Xiaojun Kuang, Shi Liu, Shiqing Deng, Jun Chen
Abstract
Owing to their wide application in oxide-based electrochemical and energy devices, ion conductors have attracted considerable attention. However, the ionic conductivity of the developed systems is still too low to satisfy the low-temperature application. In this study, by developing the emergent interphase strain engineering method, we achieve a colossal ionic conductivity in SrZrO 3 – x MgO nanocomposite films, which is over one order of magnitude higher than that of the currently widely used yttria-stabilized zirconia below 673 K. Atomic-scale electron microscopy studies ascribe this superior ionic conductivity to the periodically well-aligned SrZrO 3 and MgO nanopillars that feature coherent interfaces. Wherein, a tensile strain as large as +1.7% is introduced into SrZrO 3, expanding the c -lattice and distorting the oxygen octahedra to decrease the oxygen migration energy. Combining with theoretical assessments, we clarify the strain-dependent oxygen migration path and energy and unravel the mechanisms for strain-tuned ionic conductivity. This study provides a new scope for the property improvement of wide-range ion conductors by strain engineering.