【作者】 余华；

【导师】 熊光楠；

【作者基本信息】 天津理工大学 ， 凝聚态物理， 2002， 硕士

【摘要】 随着信息网络化的发展，人们要求各个领域的信息均以数字化的形式存在，以方便信息的处理、传输和存储。在医疗领域，医院中科室的信息网络化势在必行，医院网络化的瓶颈在于放射科的胶片图像无法数字化，无法进行传输。数字化影像仪（CR）正是解决了这一难题得到了医疗人士的普遍认可。因而数字化影像技术的发展成为当前一个时期内国际医疗系统技术革新中重点的重点。CR是利用其核心部分影像板（IP）利用电子空穴对的形式将影像存储于IP板的光存储发光材料BaFBr∶Eu²⁺中，然后通过光激励释光的方法检测出来。但是BaFBr∶Eu²⁺的激励波长恰好落在笨重昂贵的YAG倍频或使用不便的He-Ne激光器波长范围内，随着半导体激光器的发展，出现的小巧价廉的半导体激光器，如果用半导体激光器取代气体激光器或需要水冷的固体激光器作为激励光源，那么CR仪的成本和体积都将大幅度下降，但是价廉小巧的半导体激光器的波长在650nm或更长，这就对IP板提出了更高的要求，即光存储发光材料BaFBr∶Eu²⁺要通过一定的手段使激励波长红移至650nm或更长。国际上通常采用的方法是改变基质的组份使之禁带宽度变窄来实现这一目的，这一方法虽然有效地使激励波长发生红移，但也使材料的综合性质降低，如何能够既不改变机制的组分使之保持综合性能上的优势，同时又能使激励波长发生红移且保持较高的发光强度?本论文则是利用掺杂金属离子的方法组构缔合型色心的手段实现了这一改变，并且对于缔合型色心的结构及其性质进行了系统而深入的研究，研究中的创新点如下：一、在不改变基质组分，保持BaFBr∶Eu²⁺基质在综合性能优势的前提下，创造性的提出了掺入金属离子形成缔合型色心的方法促使BaFBr∶Eu²⁺的光激励波长红移并保持较高的发光强度。实验中通过巧妙选择掺入金属离子化合物和对其合成工艺的探索制备出几种在发光强度上达到或超过实用水平，并能使用小巧价廉的半导体激光器作为激励光源的缔合色心型发光材料BaFBr∶Eu²⁺，某些化合物已经申报专利。该类材料的研制成功在实用上使CR仪摆脱了采用笨重、使用不变的气体激光器的历史，降低了CR仪的成本与体积。由于没有改变基质BaFBr∶Eu²⁺的组分，保持其在综合性能优势，故同时也简化了IP板的制作工艺。二、首次通过理论分析找出缔合型色心在光激励发光与热激励发光中的内在联系，得出缔合型色心是由受掺杂离子微扰的F（Br^-）心所形成的。并且通过热激励发光的分析，找出了合成工艺的差异对缔合色心型光存储发光材料BaFBr∶Eu²⁺制备影响的本质。三、首次在拉曼光谱中观测到了缔合型色心中掺杂金属离子在高频移区出现的高频局域振动峰。首次提出了拉曼散射因子K的概念，对这一现象予以解释。这对于解释基质材料中掺杂离子的拉曼光谱性质有着普遍的理论意义。四、分析提出了不同缔合型色心的结构模型，利用拉曼光谱和电子顺磁共振谱对缔合色心中掺杂离子与F（Br^-）心各自的性质、相对位置、影响关系等做了系统表征，验证了所提出缔合型色心结构模型的正确性，首次在ESR谱中观测到新结构的产生并将其归属为O_Br^-心产生的信号。首次提出在缔合色心型光存储发光材料BaFBr∶Eu²⁺中O_Br^-心是一种有效的空穴陷阱。更多还原

【Abstract】 The information transmitted online is in the form of digit. In the hospital network isimperative. Then, in radioactive department, only if film image can be changed into digitform, it can be shared through network. The invention of CR can develop digital filmtechnique. CR uses its IP to save the image in BaFBr: Eu²⁺, then it can be detected throughphotostimulated luminescence. However, the BaFBr: Eu²⁺ photostimulated wavelength is closeto either YAG （ large and expensive） or He-Ne （ inconvenience） laser. If the semiconductorlaser, which is small and cheap, can replace the two lasers mentioned above, both the priceand size will decrease. However, the laser wavelength should be above 650nm. In this case,there’s a higher requirement for the BaFBr:Eu²⁺, that means its wavelength should be redshifted until it’s over 650nm. It is widely used to change the host component to narrow downthe width of the gap. This method can reduce the comprehensive properties, although it canred shifted the wavelength. Without changing the host component, how to keep the sameexcellent comprehensive properties, while red shifting the wavelength, and keeping the strongintensity? This paper has accomplished these changes by doping the different metal ions toform the complex color center, and further research on the structure and properties of complexcolor center has been done. The followings are some of the creative aspects.1. It put forward the idea of adding the metal ions to form complex color centers to red shiftthe BaFBr:Eu²⁺ laser wavelength, while keeping the strong luminescent, without changingthe host component, and keeping the excellence in comprehensive properties. During theexperiment, the new type of complex color center materials are made and have beenapplied to patent. IP can use cheap and tiny semiconductor laser as photostimulated source,.2. It is the first time, through theory analysis, the interrelationship of complex color centerbetween photostimulated luminescence and thermalstimulated luminescence has beenfound. Then reach the conclusion that complex color center is formed by F（Br^-）, which isinfluenced by doped metal ions. The result above has been applied to analysis differentsynthesis of BaFBr:Eu²⁺ doped metal ions successfully.3. It is the first time to observe the Raman peak in high frequency region due to the fact of complex color center doped with metal ions in Raman spectra. The conception of Raman diffraction factor K has been brought up and explained, which has theory significance to explain the Raman spectra properties of host material doped with metal ions.4. Different complex color centers construction models have been set by Raman and ESR spectra. It is the first time to observe new ESR signal, which belongs to O_Br^- centers. And O_Br^- centers is efficient vacancy traps by the experiment analysis.更多还原