Positron annihilation, thermoluminescence, and optical absorption measurements were applied with the aid of several annealing and diffusion procedures to investigate the nature of point defects in Y3Al5O12 single crystals. By annealing at 1500C in air or O, and diffusing Al into a Ce doped Y3Al5O12 single crystal, a reduction of nearly two orders of magnitude in vacancy concentration was observed. Scintillation measurements showed a significant improvement in energy resolution after Al diffusion. This revealed the presence of vacancy-defect complexes, which were most likely to be associated with cation antisites in Y3Al5O12 crystals.

Identification of Defects in Y3Al5O12 Crystals by Positron Annihilation Spectroscopy. F.A.Selim, D.Solodovnikov, M.H.Weber, K.G.Lynn: Applied Physics Letters, 2007, 91[10], 104105