Crystal-isotropicity dependence of ionic conductivity enhancement at strained interfaces

• Analyze the isotropicity dependence of interfacial strain induced lattice expansion
• Reveal the isotropicity dependence between interfacial strain and ionic conductivity
• Study temperature dependence of correlation between ionic conductivity and lattice isotropicity

In the solid state ionic field, lattice strain is ubiquitous at heterostructural crystal interfaces and can lead to enormous variation in the transport efficiency of ions along the as-formed strained interfaces. In particular, substantial experimental work has been focused on Y-doped ZrO2 (YSZ), the O2 − ionic conductivity of which can be enhanced ~ 104 times under a 4% lattice strain. Despite the consistence that theoretical modeling and computing finds with such an experimental enhancement, a fundamental investigation into the isotropicity dependence of ionic conduction in strained crystal interfaces is still lacking. In this report, we investigate the isotropicity dependence of ionic conduction in arbitrary orthorhombic crystals and reveal the intrinsic conduction enhancement upon applying strain at any designated crystal orientation. Our work provides fundamental basis for rational strain engineering of a crystal in general, the ionic conduction of which is subject to enhancement for energy applications.