Identification of defects in Y3Al5O12 crystals by positron annihilation spectroscopy

Abstract

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 (YAG) single crystals. By annealing at 1500°C in air or O, and diffusing Al into a Ce doped YAG 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 study revealed the presence of vacancy-defect complexes, most likely associated with cation antisites in YAG crystals.