Gd3(Ga,Al)5O12闪烁陶瓷阵列低成本制备及性能调控

Cerium doped gadolinium gallium aluminum garnet ceramics has the potential of becoming the next generation scintillation material for medical imaging CT detectors, for their superior properties like high light output, fast decay and low afterglow. It is also shows distinct advantages in compare with the existing public security CT detector materials. In order to realize 2D or 3D spatial resolution, scintillators should be processed into arrays with particular size. Because of their high hardness and brittleness, ceramic arrays prepared by mechanical machining methods can meet the necessary performance, but material utilization and production efficiency is low. In this project, green bodies will be shaped with gel casting method and sintered under oxygen atmosphere. As a result, ceramic scintillator arrays with perfectly controlled pixels will be prepared in one step. Based on combination of experimental studies and atomic simulation, this project will systematically investigate the influence of intrinsic defects on the scintillation performance of cerium doped gadolinium gallium aluminum garnet ceramics. The effects of material preparation parameters and ion codoping on the valence states of Ce luminescence centers will be studied, as well as the formation of structural/electronic defects. The physical mechanism of scintillation process involving defects and Ce4+ ions will also be studied. Finally, this project will look for new ways of defect engineering to tune the scintillation properties, such as light yield, scintillation decay, afterglow and radiation resistance.

铈掺杂钆镓铝石榴石陶瓷具有高光输出、快衰减、低余辉等优异性能，有望成为新一代医学成像CT探测器的关键材料，较现有安检CT探测器材料也展现出极大的竞争优势。在CT探测器的应用中，为实现二维或三维的空间分辨，必须将闪烁材料加工成具有特定设计规格的阵列。由于陶瓷硬度高、脆性大，常规机械加工阵列的制作方式，不仅效率低，难度高，而且材料损耗严重。本项目拟采用凝胶注模工艺进行素坯成型，并结合氧气氛烧结，实现闪烁陶瓷阵列像素粒子精确控制与一体化制备。在此基础上，结合第一性原理计算，研究铈掺杂钆镓铝石榴石陶瓷内部缺陷对闪烁性能的作用机制，阐明制备工艺与离子共掺对发光中心铈离子价态以及结构/电子缺陷的影响规律，完善电子缺陷与Ce4+离子参与闪烁发光的物理模型，最终实现缺陷工程对闪烁陶瓷阵列光输出、闪烁衰减、余辉以及抗辐照等闪烁性能的有效调控。

铈掺杂钆镓铝石榴石(GGAG:Ce)陶瓷具有高光输出、快衰减、低余辉等优异性能，有望成为新一代医学成像CT探测器的关键材料，较现有安检CT探测器材料也展现出极大的竞争优势。在项目经费支持下，我们开展了GGAG:Ce闪烁陶瓷阵列低成本制备与性能调控方面的研究。本项目发现当Gd3+部分被离子半径更小的Y3+取代时，微小的晶格畸变或声子振动将有助于提高间隙离子的迁移率，降低陶瓷的烧结活化能，进而提高陶瓷透过率至81%，其光输出也从55000ph/MeV提升至61000ph/MeV。陶瓷透过率与光输出的提升，有利于陶瓷获得更高的能量分辨率，这在PET探测器中的应用是非常重要的。.此外，本项目还对该GYGAG:Ce,Mn,Si材料的光学热稳定性进行了系统的研究，其激活能分别可达0.7651 eV和0.5057 eV；热释光谱分析得到电子陷阱的深度主要集中在0.86 eV、1.03 eV和1.18 eV处，极可能是氧空位。这些缺陷有助于保持陶瓷荧光体良好的热稳定性。发现通过Mn2+/Si4+掺杂实现GYGAG高透明陶瓷的红光及远红光发射；共掺Ce3+离子增强蓝光区域吸收和Mn2+发射，结果与植物色素PFR的吸收带匹配，有望应用在植物照明中用于调节植物的生长。GYGAG:Ce闪烁陶瓷热稳定性的研究，可为该材料在实际工况下的应用提供了理论支撑。基于陶瓷性能调节方面的基础研究，总共发表了11篇SCI学术论文，受邀参加两次学术报告并获得同行较高的认可度。