离子掺杂BSO晶体的生长与性能研究+实验分析 摘要：硅酸铋晶体（BSO:Bi4Si3O12）是一种新型的快计时重闪烁晶体，广泛应用于高能物理、核物理、核医学成像、地理勘探等领域。其晶体结构与锗酸铋（BGO:Bi4Ge3O12）晶体结构相同，闪烁性能均来源于Bi的激发，在某些领域，BSO晶体能够作为BGO晶体的替代品使用，并且BSO有望在双读出领域获得比BGO更具价值的应用。然而，BSO的光输出不大，仅为BGO的20%，这严重限制了其进一步的广泛应用。离子掺杂是改善BSO晶体性能的重要手段之一，人们先后进行过Ce、Nd、Eu、Fe和Cr等稀土离子或过渡金属离子掺杂的改性试验。
本实验通过二步合成法制备了BSO以及掺杂BSO原料，通过XRD测试分析得出合成的原料为纯相。采用坩埚下降法生长出BSO单晶以及掺杂浓度为5at%的Ge:BSO晶体，测试了Ge:BSO晶体的发光衰减时间，其三个分量分别为5ns，26ns，100ns。测试了荧光发射光谱，发射峰值波长为469nm（λex=285nm）。对比BSO晶体的相关实验结果，分析并解释了Ge掺杂对BSO晶体光学性能的影响。
关键词： BSO；Ge:BSO；晶体生长；坩埚下降法
Growth and Properties of Doped BSO Crystals
Abstract: Bismuth silicate (BSO:Bi4Si3O12) crystal is a novel dense and fast scintillator for various applications in high energy physics, nuclear physics, nuclear medical imaging and other industries. BSO has the same crystalline structure as BGO and its scintillation comes from the excitation of bismuth similarly as in BGO. It can be used as the alternative of BGO in some applications. Besides, BSO has the possible more valuable applications than BGO in dual-readout field. However, the light output pure BSO crystal is as small as 20% of BGO, which is severely limits the further extensive application of BSO. It is known that ion doping is one of the important means to perfect the properties of BSO crystal. A lot of researches were made to study the scintillation properties of BSO crystal doped with some rare-earth ions or transition metal ions such as Ce, Nd, Eu, Fe and Cr.
This experiments sintered the raw materials of BSO and doped BSO through two-step synthesis method. Powder X-ray diffraction (XRD) was performed to prove that the solid phase of the raw material is pure. Then, BSO and Ge:BSO crystal with 5at% dosage concentration were grown by the Bridgman growth technique. Three luminous decay constants of Ge:BSO crystal was measured to be 5ns, 26ns, 100ns, respectively and its emission peak of the fluorescence emission spectrum was examined to be 469nm(λex=285nm). When analyzed comparing with some results of BSO crystal, the effects of optical properties of BSO with Ge doping could be explained.
Keywords: BSO; Ge:BSO; crystal growth; Bridgman growth
目 录
1 绪 论 1
1.1 硅酸铋晶体简介 1
1.2 掺杂BSO研究现状 2
1.3 生长方法 2
1.4 性能研究 5
1.4.1 透射光谱 5
1.4.2 能谱与光产额 6
1.4.3 激发发射光谱 7
1.4.4 衰减时间 8
1.5 论文选题依据 9
2 实验部分 10
2.1 实验方案设计 10
2.2 实验过程 10
2.2.1 晶体生长 10
2.2.1.1 原料合成 10
2.2.1.2 下降法生长 11
2.2.2 样品加工 13
2.2.3 光学性能测试 13
2.2.3.1 衰减时间测试 13
2.2.3.2 荧光发射光谱测试 13
2.3 实验仪器和设备 13
3 实验结果与讨论 16
3.1 晶体生长 16
3.1.1 原料合成 16
3.1.2 下降法生长 18
3.2 样品加工 19
3.2.1 冷加工 19
3.2.2 晶面定向 19
3.3 光学性能测试分析 21
3.3.1 衰减时间测试 21
3.3.2 发射光谱测试 22
4 结 论 23
致 谢 24
参考文献 25,3716