First Principal calculations of carbon impurity and oxygen vacancy binding in perovskite BaZrO 3 under bi-axail (001) strain

The binding between carbon-replacing Zr (C_Zr) and oxygen vacancies (V_o) in bi-axially strained BaZrO₃has been investigated using density functional theory calculations. The binding energy of V_o-C_Zrhas been examined for compressive and tensile strains of ±1%, ±2%, ±3%, and ±4% within the (001) plane. The results indicate that carbonate ion is generated when C_Zrdopant is present in strained BaZrO₃. The local vibration frequencies of the carbonate group center have been computed at approximately 1063 cm^-1and 1410 cm^-1, indicating that the defect is both infrared and Raman active. The V_o-C_Zrcomplex's binding energy increases consistently with tensile strain, achieving 1.38 eV at 4%, demonstrating that the electrically active oxygen vacancy is effectively pinned. The binding energy varies slightly before a dramatic drop (0.78 eV) at a high value (4%) of compressive strain, indicating the trapping/releasing of V_ovia compressive strain. Our results provide evidence that the combination of carbon impurities and bi-axial strain is an effective method for adjusting the mobility of electrically active oxygen vacancies and regulating the electrical properties of perovskite BaZrO₃thin films.