【作者】 张海亮；

【导师】 左洪波；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2007， 硕士

【摘要】 蓝宝石光学窗口在空间环境服役时,将会受到不同射线(如γ射线、X射线)以及离子流(如电子、质子等)的辐照作用,使其光学性质及结构发生变化,影响使用性能。本文选取了有代表性的γ射线及电子,研究了SAPMAC法蓝宝石窗口经γ射线及电子辐照后的光学性能及结构的变化。SAPMAC法蓝宝石成分分析结果显示,晶体杂质含量较低,质量较高。原子力显微镜(AFM)实验表明,γ射线辐照对蓝宝石表面粗糙度影响不大,而电子辐照使得蓝宝石表面粗糙度增加。通过对蓝宝石辐照前后的吸收光谱及荧光光谱分析,发现蓝宝石光学窗口经γ射线和电子辐照后在紫外可见波段表现出较强的吸收,以206nm、238nm和256nm为中心的紫外吸收带对应着410nm、480nm和506nm的发光。结合γ射线和电子的辐照效应我们认为这是晶体中F和F+色心引起的。电子顺磁共振(EPR)实验结果表明,经γ射线及电子辐照后蓝宝石中产生了F+色心,由于蓝宝石中F3+色心浓度较小,电子顺磁共振谱上未发现明显信号。同时由于SAPMAC法蓝宝石质量较高,EPR谱图上未出现Fe3+和Cr3+等其它生长方法常见的杂质离子峰值。热释光(TL)实验结果显示,经γ射线辐照后蓝宝石在219℃、223℃和216℃产生新的吸收峰值,而电子辐照后在223℃和242℃产生新的吸收峰值,结合文献报道得出这几处峰值是由于F型色心所引起的,同时发现这几处吸收峰值强度较大,而且是稳定的热释光峰值。通过对辐照前后蓝宝石的正电子湮灭(PAT)寿命谱分析,发现蓝宝石经γ射线辐照后,正电子寿命τ1变化不大,而经电子辐照后,正电子寿命τ1变化较大。随着γ射线及电子辐照剂量的增加,其正电子寿命增大,说明蓝宝石缺陷浓度随着辐照剂量的增加而增加。对比蓝宝石在1200℃空气炉中保温3h前后的吸收光谱显示,在紫外可见波段未出现明显的吸收峰值,说明退火后蓝宝石中的色心浓度基本消失。更多还原

【Abstract】 The optical window of sapphire will be irradiated by rays and ion beam during it’s service, such asγ-ray and electron flow. The optical capability will be reduced. We choose the typicalγ-ray and electron flow to irradiate optical window of sapphire grown by SAPMAC method and changes in optical and structural properties were investigated in this paper.The PIXE result indicates that the sapphire grown by SAPMAC method has low impurity content. AFM showsγ-ray has a little impact on the surface roughness of sapphire, however electron flow damage the surface roughness of sapphire more greatly. The absorption spectra and fluorescence spectra of large sapphire irradiated byγ-ray and electron flow was measured. The experimental results show there are some absorption peaks of 206 nm, 238 nm and 256 nm; the fluorescence spectra correspond to these peaks are 410nm, 480nm and 506nm. Further study suggests the color centers are cause by the presence of oxygen vacancy (F and F+). The EPR display that there are F+ color centers in sapphire after irradiated byγ-ray and electron flow. Because of the concentration of F3+ in sapphire is low, so there isn’t any signal in the EPR spectra. And Fe3+ and Cr3+ signal was also not detected in EPR spectra. The results of TL reveal that there are new peaks at 216℃、219℃and 223℃induced byγ-ray and new peaks at 223℃and 242℃are induced by electron flow. The peaks at these temperatures are due to F color centers in sapphire and the intensity of these peaks is high and stabilized. The analysis of PAT announces that after irradiated byγ-ray and electron flow the positron life ofτ1 changes a little, whereas after irradiated by electron flow the positron life ofτ1 changes greatly. Along with the increase of the dose ofγ-ray and electron flow, the concentration of defects in sapphire also increased.Measures to bring down the concentration of color centers in sapphire are also proposed. After 3h of annealing in air, there is no obvious signal detected in the absorption spectra.更多还原