Luminescence studies of Ce : YAG using vacuum ultraviolet synchrotron radiation

Photoluminescence spectrum of Ce:YAG single crystal was studied employing vacuum ultraviolet (VUV) synchrotron radiation. Intrinsic absorption edge at about 52,000 cm(-1) was observed in the absorption spectrum. From the VUV excitation spectrum, the energy of the highest d-component of 53,191 cm(-1) (188 nm) for the Ce3+ ions in YAG was obtained at 300 K. The disappearance of the third 5d level at 37,735 cm(-1) (265 nm) in absorption and excitation spectra in our samples may be due to the impurity Fe3+ ions absorption. (C) 2006 Elsevier Ltd. All rights reserved.

V^3＋：YAG晶体的生长、色心与光谱性能研究

采用石墨电阻加热的温梯法生长了V：YAG晶体，晶体的不同部位呈现两种不同的颜色：浅绿色和黄褐色．通过对比分析不同颜色V：YAG晶体的室温吸收光谱，推断出石墨发热体高温下扩散出来的C可以起到还原作用，提高晶体中V^3＋tetra离子的浓度，同时诱导了F心的形成．在1300℃下，对不同颜色的V：YAG晶体进行真空退火处理，发现处于八面体格位中的V^3＋离子在热激发作用下与近邻的四面体格位Al^3＋离子存在置换反应，由此产生一定浓度的四面体格位V^3＋离子．同时，F心在退火过程中被完全消除，释放出来的自由电子被

Comparison of ZnO films grown on before- and after-vapor transport equilibration (VTE) LiAlO2 substrates by pulsed laser deposition (PLD)

About Phi 45 mm LiAlO2 single crystal was grown by Czochralski (Cz) technique. However, the full-width at half-maximum (FWHM) value was high to 116.9 arcsec. After three vapor transport equilibration (VTE) processes, we can obtain high-quality LiAlO2 slice with the FWHM value of 44.2 arcsec. ZnO films were fabricated on as-grown slices and after-VTE ones by pulsed laser deposition (PLD). It was found that ZnO films on the two slices have similar crystallinity, optical transmittance and optical band gap at room temperature. These results not only show that LAO substrate is suitable for ZnO growth, but also prove that the crystal quality of LAO substrate slightly affects the structural and optical properties of ZnO film.

提拉法生长镓酸锂晶体及缺陷研究

研究了提拉法生长的镓酸锂单晶的生长习性和结晶质量。晶体表面呈乳白色且表面粗糙。通过光学显微镜、四晶X射线衍射、透射光谱和电感耦合等离子体发射光谱对样品进行了表征，结果表明，在（001）面的抛光样品上存在三种缺陷：[110]和[-110]方向的十字线、[010]方向排列的气泡包裹物以及平行于（010）面的界面，界面的产生起因于（010）晶面的滑移；晶体的结晶质量从顶部到底部逐渐下降，这是由于在生长过程中氧化锂的挥发导致熔体成分偏离化学计量比造成的。

在Sr～2+α_BBO单晶衬底上生长β_BBO薄膜的研究

Crystalline beta-BBO thin films were successfully prepared on (001)-oriented Sr2+-doped alpha-BBO substrates by using liquid phase epitaxy, pulsed laser deposition and vapor transport equilibration techniques. The films were characterized by X-ray diffraction and X-ray rocking curve. The present results manifest that the beta-BBO thin films grown on Sr2+-doped alpha-BBO substrates have larger degree of orientation f value and smaller X-ray rocking curve FWHM than the ones grown on other reported substrates. Compared with other substrates, alpha-BBO has the similar structure, the same UV cutoff and the same chemical properties to beta-BBO. These results reveal that Sr2+-doped alpha-BBO single crystal may be a promising substrate proper to the growth of beta-BBO films.

Study on growth and properties of novel gamma-LiAlO2 substrate

Transparent gamma-LiAlO2 single crystal has been grown by Temperature Gradient technique. The surface of the wafer annealed in O-2-atmosphere at 1100 degrees C for 70 h became opaque and Li-poor phase (LiAl5O8); while, that annealed in Li-rich atmosphere kept transparent and smooth. The full-width at half maximum value dropped to 30 arcsecs when the wafer was annealed in Li-rich atmosphere. That annealed in O-2-atmosphere increased to 78 arcsec. Compared with absorption spectra, we can conclude that the 196 nm absorption peak was caused by Li vacancies and the 736 nm peak was caused by O vacancies.

Mg，Ti共掺Al2O3透明多晶陶瓷光谱性能研究

Transparent polycrystalline MgO and TiO2 codoped Al2O3 ceramics were fabricated by conventional solid-state pressureless processing. The absorption, emission and excitation spectra of ( Mg, Ti : Al2O3 ceramics were measured. Owing to charge compensation of Mg2+, only UV absorption around 250nm was observed due to O2- -> Ti4+ charge transfer transitions (CT) when Ti content was low. As a result, the emission peaks of isolated Ti4+ ion located at 280-290nm and 410-420nm were observed. Besides absorption peak of V, ion, the characteristic absorption peak of V, ion centered at 490nm was observed in Mg, Ti) : Al2O3 ceramics when Ti content was high. The emission spectra of Ti3+, ion in polycrystalline Al2O3 ceramics coincide with that of Ti: Al2O3 single crystal.

Structural, optical and electrical properties of ZnO films grown on c-plane sapphire and (100)gamma-LiAlO2 by pulse laser deposition

ZnO thin films were grown on single-crystal gamma-LiAlO2 (LAO) and sapphire (0001) substrate by pulsed laser deposition (PLD). The structural, optical and electrical properties of ZnO films were investigated. The results show that LAO is more suitable for fabricating ZnO films than sapphire substrate and the highest-quality ZnO film was attained on LAO at the substrate temperature of 550 degrees C. However, when the substrate temperature rises to 700 degrees C, lithium would diffuse from the substrate (LAO) into ZnO film which makes ZnO film on LAO becomes polycrystalline without preferred orientation, the stress in ZnO film increases dominantly and the resistivity of the film decreases exponentially. (c) 2005 Elsevier B.V. All rights reserved.

显微成像荧光屏用无机闪烁单晶薄膜的研究进展

随着第三代同步辐射源的出现，由荧光屏和CCD耦合组成的、具有亚微米级空间分辨率、快速在线成像功能的探测器在医疗、安检、工业、科研等领域将会得到广泛应用．本文主要综述了成像荧光屏用材料的概况和发展趋势，重点阐述了闪烁单晶薄膜的研究及发展情况．

γ-LiAlO2晶体生长、改性和热学性质研究

采用快速提拉法生长出了透明、完整的γ-LIAlO2晶体，但是晶体的高熔点和易挥发性限制了γ-LiAlO2晶体质量．采用气相传输平衡法（vapor transport equilibration technique，VTE）工艺对晶体改性，半高宽（FWHM）值从116．9arcsec降至44．2arcsec，继续升高VTE处理温度至1300℃，FWHM值反而升高至55．2arcsec．快速提拉法生长出来晶体，[100]方向和[001]方向的热膨胀系数分别为17．2398×10^-6／K，10．7664×10

氧化铝透明陶瓷中Cr3+的发光性能

采用传统无压烧结工艺制备出透明性良好的掺Cr3+氧化铝陶瓷;测定了陶瓷的吸收光谱、发射光谱和激发光谱。结果表明,氧化铝陶瓷吸收峰与红宝石单晶一致,吸收截面大小与单晶相近;陶瓷中Cr3+离子所处格位的晶体场强较单晶弱,但其发射谱仍有较好的锐线发射;陶瓷中微量添加剂以及晶界的存在使得Al2O3晶胞发生畸变,造成其发射峰宽化。

激光二极管抽运Na，Yb共掺CaF2晶体自调Q激光特性的研究

利用激光二极管（LD）抽运新型Na．Yb共掺CaF2（Na．Yb：CaF2）晶体，获得了1．05μm的自调Q激光输出。利用透射率1％的耦合输出镜，得到最低激光输出的抽运阈值功率仅为70mW。在透射率为2％的输出镜条件下，得到最大输出激光功率为390mw，此时激光的斜度效率达到20%。实验详细记录了自调Q脉冲的周期和宽度随抽运功率的变化关系，随着抽运功率的增加，自调Q脉冲的周期和宽度呈指数衰减。同时，还采用单棱镜进行光谱调谐实验，获得了1036～1059nm的自调Q激光调谐输出。

提拉法生长大尺寸γ-LiAlO2单晶的研究(英文)

由于与GaN晶格失配小(约1．4％)，γ-LiAlO2单晶有望成为一种很有希望的GaN外延衬底材料。本文使用提拉法生长出了尺寸达Ф5×50mm^3的γ-LiAlO2单晶。对该晶体毛坯的各个有代表性的位置作了X射线粉末衍射(XRPD)分析，结果表明仅仅在晶体毛坯的底部生成了一种缺锂相(LiAl5O8)。γ-LiAlO2晶体化学稳定性差，在室温时轻微水解。当在空气中于1100℃退火70h，γ-LiAlO2晶体挥发出锂组分，在表面产生缺锂相(LiAl5O8)。值得注意的是，在γ-LiAlO2晶体的红外光谱区不存

r面白宝石单晶的温梯法生长及缺陷研究

本文描述使用温梯法（TGT）生长（1-↑102）方向的白宝石单晶，应用X射线双晶摇摆曲线（XRC）测定了晶体内部的完整性，再利用KOH熔体腐蚀出样品的r面（1-↑102）上的位错蚀坑，借助扫描电子显微镜（SEM）进行观察，发现r面白宝石的位错腐蚀坑呈等腰三角形，并且有台阶状结构，并分析了位错的成因。

透明导电氧化物β-Ga2O3单晶生长的研究进展

本文对β-Ga2O3单晶体的研究情况进行了综合，主要介绍了β-Ga2O3单晶体的生长方法：Verneuil法、提拉法和浮区法生长技术，并简单介绍了β-Ga2O3单晶体的光学和电学性质及其在GaN衬底方面的应用。β-Ga2O3单晶体的优异性质使其可以成为新一代的透明导电材料。