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Abstract: Gd1.99− x Y x Ce0.01SiO5 (Ce:GYSO) crystals (, 0.0995, 0.199) have been grown by the Czochralski (Cz) method. Crystal structure and the distribution coefficients of Ce have been determined for all three crystals. Spectroscopic measurements indicate that optical transmittance and luminescence intensity of Gd1.99− x Y x Ce0.01SiO5 (, 0.199) crystals are substantially higher than those of Ce:Gd2SiO5 (Ce:GSO), especially at , which makes them good candidate materials for scintillation applications. The particularly important result is that the alloyed Ce:GYSO crystals can be grown easily by the Cz method and, unlike Ce:GSO, they do not undergo cleavage during the growth process or subsequent mechanical treatment. [Copyright &y& Elsevier]

Abstract: Undoped Y2SiO5 single crystal was grown by the Czochralski method. The samples were optically polished after orienting and cutting. The rhombus and quadrangular dislocation etching pits, the low-angle grain boundaries and the inclusions in the samples were observed using optical microscope and scanning electron microscope. The absorption spectra were measured before and after H2 annealing or air annealing. The absorption edge of Y2SiO5 crystal was determined to be about 202 nm. The absorption coefficient of Y2SiO5 crystal decreased after H2 annealing and obviously increased after air annealing. [Copyright &y& Elsevier]

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]

Abstract: Yb: YAlO3 (YAP) (15at%) and Yb: Y3Al5O12 (YAG)(15at%) have been grown using the Czochralski method. Their absorption and fluorescence spectra were measured at room temperature and important spectroscopic parameters were calculated. Through the comparison of spectroscopic parameters of Yb:YAP and Yb: YAG, all results indicate that 15at% Yb:YAP crystal is a potential candidate used for compact, efficient thin chip lasers when the laser output wavelength is 1012 or 1038nm. [Copyright &y& Elsevier]

Abstract: Undoped LaAlO3 and Ce-doped LaAlO3 single crystals were grown by the Czochralski process. The segregation coefficient of cerium ions in 1at% Ce: LaAlO3 is 0.28. The undoped LaAlO3 and Ce-doped LaAlO3 single crystals were characterized by infrared transmission spectra and ultraviolet/visible/near-IR absorption spectra. It was observed that the band-to-band absorption of LaAlO3 host is around 209nm. Four characteristic f–f transitions of Ce3+ ion at 1923, 2354, 2669, and 3728cm-1 and five f–d transitions around 198, 206, 214, 246, and 316nm in the Ce-doped LaAlO3 crystal were observed. Strong emission around 410nm was also observed at excitation of 317nm in the Ce-doped LaAlO3 single crystal. [Copyright &y& Elsevier]