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Abstract: The absorption spectra of the undoped Y2SiO5 and Eu3+-doped Y2SiO5 crystals grown by the Czochralski technique were compared before and after annealing and, similarly, the unannealed and annealed crystals after γ-ray irradiation. The absorption bands of Eu2+ ions with peaks at 300 and 390nm were observed in the as-grown Y2SiO5:Eu3+ crystal. These peaks were more intense in H2-annealed and irradiated Y2SiO5:Eu3+ crystals. The additional absorption peaks at 260 and 320-330nm which were attributed to F color centers and O − hole centers were observed in irradiated undoped Y2SiO5 and Y2SiO5:Eu3+ crystals, respectively. [Copyright &y& Elsevier]

Abstract: The dark-brown colored 5at% Yb-doped YAlO3 (Yb:YAP) single crystal was grown successfully by temperature gradient technique (TGT) for the first time. The TGT-grown Yb:YAP crystal with the perovskite structure and excellent crystallization perfection were confirmed by the X-ray diffractions techniques. The dark-brown color of TGT-Yb:YAP crystal turned into the colorless after annealing in the air at 1200°C for 10h. The absorption spectra, LD-excited infrared emission and X-ray excited luminescence spectra of the air-annealed Yb:YAP single crystal were investigated at the room temperature. The results indicate that the TGT-Yb:YAP single crystals can be used for the laser and scintillation applications. [Copyright &y& Elsevier]

Abstract: Five absorption bands, at 227, 300, 340, 370 and 457nm, 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 457nm were identified as belonging to the Ce3+-ion in the YAG crystal. A near UV optical emission band at 398nm was observed, with an excitation spectrum containing two bands, at 235 and 370nm. No fluorescence was detected under 300nm excitation. The pair of absorption bands at 235 and 370nm and the absorption band at 300nm 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). [Copyright &y& Elsevier]