Effect of air annealing on the spectral properties of Ce:Y3Al5O12 single crystals grown by the temperature gradient technique

Five absorption bands, at 227, 300, 340, 370 and 457 nm, were observed in the optical absorption spectrum of Ce:Y3Al5O12 (Ce:YAG) crystals grown by the temperature gradient technique (TGT). The absorption bands at 227, 340, and 457 nm were identified as belonging to the Ce3+-ion in the YAG crystal. A near UV optical emission band at 398 nm was observed, with an excitation spectrum containing two bands, at 235 and 370 nm. No fluorescence was detected under 300 nm excitation. The pair of absorption bands at 235 and 370 nm and the absorption band at 300 nm were attributed to the F- and F+-type color centers, respectively. The color centers model was also applied to explain the spectral changes in the Ce:YAG (TGT) crystal, including the reduction in the Ce3+-ion absorption intensity, after annealing in an oxidizing atmosphere (air).