Antisite defects in nonstoichiometric Lu3Al5O12:Ce ceramic scintillators

Antisite defects (ADs) in nonstoichiometric Lu3Al5O12: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,Lu-16a AD is dominant in LuAG when an Lu2O3 excess exists. Nonstoichiometric LuAG:Ce ceramic with different Lu2O3 excess were prepared to verify the calculation results. The retrieved XRD lattice constants of Lu2O3 excess LuAG:Ce ceramics fit well with DFT calculation results on Lu-Al,Lu-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,Lu-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,Lu-16a antisite defects and nearest normal Lu sites.