Optical/electrical properties of RENiO3 (RE = Pr, Nd, Sm, Gd, Dy, Ho, Er, Y and Lu) with intrinsic point defects: A first-principles study

Defects in rare-earth nickelates (RENiO3) are closely related to their metal-to-insulator phase transitions and optical/electrical properties, therefore play an important part in the applications of RENiO3. In this work, the intrinsic point defects of RENiO3 (RE = Pr, Nd, Sm, Gd, Dy, Ho, Er, Y and Lu) with stoichiometric and nonstoichiometric ratios were studied through first-principles calculations. In stoichiometric systems, the defect formation energy has the order of RE Frenkel > Cation antisite defect Ni Frenkel > O Frenkel > Schottky. Among non-stoichiometric RENiO3, the defects are prone to form in RE2O3 excessive environment as compared to those in the Ni2O3 excessive situation. In terms of electronic properties, oxygen vacancies reduce the band gap of RENiO3 and introduce a new occupied state of Ni-O. At 300 K, the conductivity of RENiO3 increases with the increase of carrier concentration. For the optical properties, the O vacancies block the infrared light and increase the transmission of visible light. The intrinsic point defects discussed in this study can not only explain the difference in defect type, but also provide a way to optimize performance of RENiO3.