BaGd2O4:Eu3+闪烁体余辉特性有效调控的研究

Dense scintillating materials have been sucessfully applied in various high-level scientific fieds such as high energy physics engineering, nuclear medical image, nation safeguard and international antiterrist activity. Some practical problems including low concentration of dopant activators, difficulty in growing large-dimension crystals with expensive cost,and the troublesome afterglow characteristics have inhibited extensive application of the developed scintillating materials. To control effectively the afterglow characteristics of practical scintillators, dense BaGd2O4:Eu3+ scintilating phosphors with self-owned intellectual property will be designed and developed by relatively enconimic and desne BaO-Gd2O3 binary system, and their microstructure will be tuned by alivolant ion codoping and isovalent ion substitution methods. The correlation between micrstructure and optical performances (especially in afterglow characteristics) will be systematically revealed by modern characterization technologies of material science and luminensece theory. The interaction mechanism between the local enviromental of BaGd2O4 host material and the luminescent Eu3+ ions will be evaluated by the famous Judd-Ofelt theroy, and the corresponding physics model on the controlled afterglow charactersitcs of scintillating materials is finally constructed. The obtained valuable resutls will be a instructive guidance to the enrichment and development of nonvel scintillating materilas in both experiment designing and theory improvement.

高密度闪烁体在高能物理工程、核医学成像、国家安全及国际反恐等高科技领域中都获得了成功的应用，但激活剂浓度偏低、大尺寸晶体生长困难且成本昂贵、余辉特性存在等实际问题限制了高密度闪烁体的进一步推广应用。为解决实用闪烁体余辉特性有效调控这一科学问题，本项目以较为廉价的BaO-Gd2O3二元系为基础，采用高温固相法合成具备自主知识产权的高密度BaGd2O4:Eu3+闪烁体，通过异价离子共掺和同价离子替代等方法调控BaGd2O4:Eu3+闪烁体的微结构进而有效调节其余辉特性，借助现代材料科学表征手段及固体发光理论系统研究BaGd2O4:Eu3+闪烁体微结构及其发光性能（尤其是余辉特性）间的相互关联，运用Judd-Ofelt理论评价BaGd2O4基质中局域环境与Eu3+的相互作用机制，重点构建闪烁材料余辉特性有效调控的物理模型，为丰富和发展新型高效闪烁材料提供关键性的实验参数和理论依据。

本项目按照同价离子取代（如通过Pr3+、Y3+或Bi3+取代Gd3+；Sr2+取代Ba2+）、或异价离子共掺（如Na+、Li+同时取代Ba2+和Gd3+）、或外掺助溶剂（如H3BO3等）等研究方案来调控BaGd2O4:Eu3+闪烁荧光粉的结构及其发光性能，尤其是在改善发光强度及调控余辉方面取得了重要成果，较好地完成了预期研究目标。.（1）获得了一步固相反应法和两步固相反应法合成BaGd2O4:Eu3+闪烁荧光粉的关键技术。二步固相反应法将高温1300 °C煅烧时间从一步法所需600 min缩短为240 min，对于节能绿色生产具有重要意义。.（2）0.1 mol% Pr3+共掺BaGd2O4:Eu3+荧光粉可将其余辉控制到未掺杂Pr3+时54.08%。但1 mol% Pr3+共掺BaGd2O4:Eu3+荧光粉的XEL发光强度仅为未掺杂时7%左右，故优化闪烁体性能时需在余辉与光产量间寻找平衡。.（3）BaGd2O4:Eu3+闪烁荧光粉XEL强度随Y3+替代Gd3+含量增加而显著增强，完全替代（x=1.8）与未替代（x =0.0）时相比，其发光强度增大了约10倍。而紫外激发时光致发光强度增强不到1.5倍。.（4）BaGd2O4:Eu3+闪烁荧光粉的XEL强度随Sr2+替代Ba2+含量逐渐替代而变化显著，发光强度最大值出现在x=0.4和x=0.6的荧光粉，比未替代（x=0.0）时发光强度增强了约20倍。此外，通过60 mol%的Sr2+替代时，余辉中较短成分从22.66 ns缩减到19.22 ns，但较长成分有所延长。.（5）Na+共掺BaGd2O4:Eu3+闪烁荧光粉，Na+最佳浓度为y=0.125，相应发光强度增强了~30%，发光增强在于Na+替代BaGd2O4基质而产生新的缺陷（缺陷簇）与其助熔剂效应相互制约的结果。.（6）Eu3+/Dy3+共掺SrGd2O4荧光粉中，Dy3+能够将吸收的能量通过电偶极-电四极相互作用有效地传递给Eu3+，从而增强其光致发光性能。在X射线激发下，XEL发光强度也增强了约2倍。.（7）研发出密度超过7.0 g/cm3硼锗碲酸盐闪烁玻璃，其XEL积分发射强度约为33.71% BGO，衰减时间为1.776 ms。发现Al2O3在空气中合成无色透明的Ce3+激活硼硅酸盐闪烁玻璃的重要作用，并研究了SiC和石墨粉的协同还原效应对其发光性能影响