Mechanism of Intrinsic Point Defects and Oxygen Diffusion in Yttrium Aluminum Garnet: First‐Principles Investigation

Formation of intrinsic point defect in yttrium aluminum garnet ( YAG ) is comprehensively investigated using first‐principles calculations. We showed that the defect formation energies of intrinsic point defects closely depend on the possible values of chemical potentials of Y , Al , and O . Both Y Al16(a) anti‐site defect, oxygen vacancy V O , and interstitial O i might be the preferred defect species when chemical potentials of Y , Al , and O vary in different areas. The O ‐related defects are also important intrinsic point defects in YAG and deserve to be further examined. The oxygen self‐diffusion are investigated and we found that energy barrier of oxygen diffusion is enhanced and decreased by neighboring Y Al16(a) and Al Y anti‐site defects, respectively. The results are used to explain the mechanism of experimental observations that Al 2 O 3 excess speeds up oxygen diffusion and that Y 2 O 3 excess suppresses oxygen diffusion in YAG .