Strain-Induced Phase and Oxygen-Vacancy Stability in Ionic Interfaces from First-Principles Calculations

Understanding interfacial chemistry is becoming crucial in materials design for heterointerfaces. Using density functional theory, we elucidate the effect of strained interfaces on phase and oxygen-vacancy stability for CeO 2 |ZrO 2, ThO 2 |ZrO 2 and CeO 2 |ThO 2 interfaces. The calculations show that ZrO 2 transforms from cubic fluorite to the orthorhombic columbite under tensile strain providing evidence of a previous experimental speculation of an unrecognized ZrO 2 phase. We also show oxygen vacancy formation energy decreases in the presence of tensile strain. As a result, the interfacial strain could be used as a knob to stabilize oxygen vacancies on either side of the interface, and control their concentration for fast-ion conductor applications.