Comparison of defect processes in REAlO₃ perovskites and RE₃Al₅O₁₂ garnets

Defects can decrease the efficiency of scintillators by trapping electrons. Here, point defects in RE AlO 3 and RE 3 Al 5 O 12 are predicted with pair potential simulations, where RE is yttrium or a trivalent rare earth cation. It was found that RE AlO 3 shows a preference for Al 2 O 3 ‐excess whereas RE 3 Al 5 O 12 most readily exhibits RE 2 O 3 ‐excess. Also, lattice volume changes for the energetically favorable intrinsic mechanisms are relatively invariant as a function of RE cation size in RE 3 Al 5 O 12 , but not in RE AlO 3 . However, in non‐stoichiometric RE 3 Al 5 O 12 , the energetically preferred disorder mechanism results in an increasing lattice expansion with increasing RE radius whereas, in non‐stoichiometric perovskites, a relatively small, radius independent, lattice contraction is predicted. These results illustrate that defect behavior in RE AlO 3 perovskites and RE 3 Al 5 O 12 garnets is quite disimilar.