Antisite defects in nonstoichiometric Lu₃Al₅O₁₂:Ce ceramic scintillators

Abstract

Antisite defects (ADs) in nonstoichiometric Lu 3 Al 5 O 12 :Ce (LuAG:Ce) were studied systematically by a combination of first‐principles calculation based on density functional theory (DFT), X‐ray diffraction (XRD), and electron spin resonance (ESR) experiments. Calculations illustrated that Lu Al,16a AD is dominant in LuAG when an Lu 2 O 3 excess exists. Nonstoichiometric LuAG:Ce ceramic with different Lu 2 O 3 excess were prepared to verify the calculation results. The retrieved XRD lattice constants of Lu 2 O 3 excess LuAG:Ce ceramics fit well with DFT calculation results on Lu Al,16a AD model, and the same distorted Ce sites in single crystals were also found in LuAG:Ce ceramics by ESR, which suggests the existence of Lu Al,16a ADs and they are dominant in nonstoichiometric LuAG:Ce ceramics, and thus measurable concentrations of ADs were detected in ceramics. This revealed that the formation of ADs is related to both temperature and chemical stoichiometry. Lu Al,16a antisite defects and nearest normal Lu sites.