Physical justification for ionic conductivity enhancement at strained coherent interfaces

Introducing lattice mismatch-induced tensile strain at hetero-interfaces may be an efficient approach to enhance ionic conductivity at moderate temperatures. Extensive theoretical and experimental research has focused on strain-versus-ionic conductivity correlations. However, the correlation between strain and ionic conductivity still lacks a systematic and quantitative investigation. In this report, we derive an analytical expression to evaluate quantitatively the strain-induced enhancement in ionic conductivity. We demonstrate that simulation and experimental data in the literature, are well explained in the framework of our derived expressions. Our studies provide a powerful platform for quantitatively designing and engineering heterostructure interfaces for a number of applications, including fuel cells/batteries and optical/magnetic devices.