闪烁晶体钨酸镉的合成、生长及性能研究

发布时间：2018-04-19 07:20

本文选题：CdWO4晶体 + Cd1-xZnxWO4固溶体　；参考：《宁波大学》2015年硕士论文

【摘要】：钨酸镉(CdWO4)单晶是一种闪烁性能优良的闪烁探测器材料,其X射线吸收系数大、发光效率较高,余辉时间短、抗辐照损伤性能强,在核医用X-ray CT、集装箱探测领域拥有极其重要的应用价值。国内外主要是运用提拉法生长钨酸镉晶体,但是提拉法生长高质量钨酸镉单晶的主要困难有:熔体挥发、沿(010)解理面开裂、包裹物的产生、晶体着色等。本文主要以钨酸镉晶体作为研究对象,研究工作主要分为以下三部分:1、CdWO4多晶料的固相合成和液相合成。优化制备工艺流程,采用固相合成法和液相合成法制备出白色钨酸镉多晶料。以液相合成法为重点,研究了反应溶液pH对原料纯度的影响,探索出满足晶体生长用原料的最佳合成条件。总结了固相合成法和液相合成法合成钨酸镉多晶料的优缺点。2、CdWO4晶体生长与性质研究。利用液相合成法合成出的高纯钨酸镉原料,通过改进生长晶体的温场、采用提拉法成功生长出较大尺寸的透明、接近无色的完整CdWO4单晶。对单晶的宏观缺陷及影响晶体生长的因素进行了研究。研究了无色、透明晶体的腐蚀、透过光谱、荧光光谱、能量分辨率、绝对光输出、荧光衰减时间性质。结果表明,CdWO4单晶在可见光区域的透过率达70%左右,荧光发光峰位于473.8 nm,即本征发光由蓝光组成,能量分辨率为7.8%,绝对光输出为20750±375 photons/MeV,CdWO4晶体衰减时间分别为1329.5 ns和11501.5 ns,与文献报道的数据进行比较、分析,结果表明采用提拉法成功生长出高质量、高性能的CdWO4单晶。3、Cd1-xZnxWO4固溶体晶体的生长与性质研究。利用高温固相合成法合成了Cd1-xZnxWO4(x=0,0.1,0.3,0.5,0.7,0.9,1.0)多晶料。粉末X射线衍射分析及结构精修结果表明,随着Zn含量的增加,固溶体的衍射峰形从CdWO4的峰形逐渐向ZnWO4的峰形过渡,晶胞参数由钨酸镉向钨酸锌过渡。通过优化工艺条件,成功生长出完整、无宏观缺陷的Cd1-xZnxWO4(x=0,0.057,0.113,0.416)固溶体单晶。研究了Cd1-xZnxWO4晶体的透过光谱、荧光光谱、能量分辨率、绝对光输出、荧光衰减时间性质。结果表明,固溶体单晶的吸收边没有变化,在350-600 nm区域的光透过率达65%左右,发射峰随Zn含量增加呈现波长红移的趋势。另外,随着Zn含量的增加,固溶体晶体的能量分辨率变大、光输出变小,对应于晶体的衰减时间的两个成分都呈增大的趋势。结合晶体生长时熔体的挥发量,少量掺锌的Cd1-xZnxWO4(x0.1)晶体是具有高闪烁性能、高生长特性的闪烁晶体。
[Abstract]:Cadmium tungstate CdWO4) single crystal is a kind of scintillation detector material with good scintillation performance. It has high X-ray absorption coefficient, high luminescence efficiency, short afterglow time and strong radiation damage resistance.Container detection has very important application value in nuclear medical X-ray.Czochralski method is mainly used to grow cadmium tungstate crystal at home and abroad. However, the main difficulties of Czochralski method in growing high quality cadmium tungstate single crystal are: melt volatilization, cracking along the cleavage surface of Czochralski (010), production of encapsulates, crystal coloration, etc.In this paper, cadmium tungstate crystal is taken as the research object. The research work is mainly divided into three parts: solid phase synthesis and liquid phase synthesis of the polycrystalline material: 1: 1 ~ (-1) CdWO4.The white cadmium tungstate polycrystalline material was prepared by solid state synthesis and liquid phase synthesis.The effect of pH on the purity of the raw material was studied with the emphasis on the liquid phase synthesis method, and the optimum synthetic conditions for the raw material for crystal growth were explored.The growth and properties of cadmium tungstate polycrystalline materials synthesized by solid phase synthesis and liquid phase synthesis were summarized.The high purity cadmium tungstate was synthesized by liquid phase synthesis. By improving the temperature field of the crystal, a large size transparent and nearly colorless CdWO4 single crystal was successfully grown by Czochralski method.The macroscopic defects of single crystal and the factors affecting crystal growth were studied.The corrosion, transmission spectrum, fluorescence spectrum, energy resolution, absolute light output and fluorescence decay time of colorless and transparent crystals are studied.The results show that the transmittance of CdWO4 crystal is about 70% in the visible region, and the fluorescence peak is at 473.8 nm, that is, the intrinsic luminescence is composed of blue light.The energy resolution is 7.8 and the absolute light output is 20750 卤375photons / MeV _ (VN) CdWO4 crystal attenuation time of 1329.5 ns and 11501.5 ns, respectively. Compared with the data reported in the literature, the results show that the Czochralski method has successfully grown high quality.Growth and Properties of High performance CdWO4 single Crystal.CD _ (1-xZn _ XW _ 4) O _ (0. 1) 0. 1 ~ 0. 3 (0. 5) 0. 7 ~ 0. 91.0) polycrystalline material was synthesized by high temperature solid state synthesis.The results of powder X-ray diffraction and structural refinement show that with the increase of Zn content, the diffraction peak of solid solution changes gradually from the peak of CdWO4 to the peak of ZnWO4, and the lattice parameters transition from cadmium tungstate to zinc tungstate.By optimizing the process conditions, the solid solution single crystals of CD _ (1-xZn _ xWO4) O _ (0.057) 0.113 ~ (3) C _ (0.416) have been successfully grown without macroscopical defects.The properties of transmission spectrum, fluorescence spectrum, energy resolution, absolute light output and fluorescence decay time of Cd1-xZnxWO4 crystal are studied.The results show that the absorption edge of the solid solution single crystal does not change and the transmittance reaches about 65% in the region of 350-600 nm. The emission peak shows the trend of wavelength red shift with the increase of Zn content.In addition, with the increase of Zn content, the energy resolution and light output of the solid solution crystal become larger and smaller, and both components corresponding to the decay time of the crystal tend to increase.A small amount of Zn doped CD _ (1-xZn _ xWO4O _ 4) x _ (0.1) crystal is a scintillation crystal with high scintillation property and high growth property combined with the volatile amount of melt during crystal growth.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ132.44;O78

【参考文献】