锗酸铋晶体的辐照损伤及热释光研究  

Study on Irradiation Damage and Thermoluminescence of Bismuth Germanate Crystal

作　　者：李培俊[1] 范世(马豈)[1] 勃.罗斯坦因 波.列考克 

机构地区：[1]中国科学院上海硅酸盐研究所 [2]西欧核子研究中心

出　　处：《无机材料学报》1991年第3期257-268,共12页Journal of Inorganic Materials

摘　　要：对不同厂家生产的大量锗酸铋晶体及若干掺杂样品,采用不同辐照源和剂量进行了实验,记录了它们的光吸收和热释光。辐照损伤来源于色心的形成,光吸收随着辐照剂量而增加,几千拉德的辐照剂量使光吸收达饱和,这可能是因为作为色心起源的缺陷数目达到了饱和。在所有情况下,吸收曲线的形状不变。吸收随时间以及在不同温度下的恢复呈现出两个区:一个快区,一个慢区。热释光曲线通常出现两个峰,第一个峰出现在100℃左右,形状不对称,为一级动力学机制,第二个峰出现在140℃左右,形状对称,它的动力学机制复杂。锗酸铋晶体经辐照后的光吸收与热释光之间有着很好的联系,每一个热释光峰都对应着色心消失的温度阈值。掺杂样品的研究表明,杂质,特别是铁对锗酸铋晶体的辐照损伤起着重要的作用。提出了能解释实验结果的模型,存在一种与铁的离子置换有关的陷阱,以及两种损伤恢复的机制,一个是局域迁移,另一个是通过价带。A number of bismuth germanate crystals produced by different firms and seve-ral doped bismuth germanate samples have been tested with different kinds of irra-diation and various doses.The optical absorption and thermoluminescence have beensystematically recorded.Irradiation damage results from the formation of colourcenter.The optical absorption increases with the doses and saturates after the irra-diation of a few thousands Rad probably due to the saturation of the number ofdefects at the origin of the colour centers.The shape of the absorption spectrumkeeps constant in all the cases.The recovery as a function of time and at differenttemperatures displays two regimes,one fast and the other slow.The thermolumines-cence spectrum consists generally of two peaks,one very asymmetric at about 100℃with first order kinetics,and the second symmetric at about 140℃,for which thekinetics is more complex.A net correlation has been observed between the absorp-tion behavior and the thermoluminescence spectrum of bismuth germanate crystals.For every thermoluminescence peak,there is a corresponding threshold of tempera-ture for the disappearance of colour centers.The study of doped samples has shown that the impurities,particularly iron,play a preponderant role in the irradiation damage of bismuth germanate crystals.A model that gives a good explanation to the observed results is proposed,thatone kind of traps associated with iron substitution ions exists and the recovery oc-curs through two different ways,localized transition or via a valence band.

关 键 词：锗酸铋 晶体 辐照损伤 热释光 

分 类 号：O614.532[理学—无机化学]