低压电子束激发场发射显示器用C12A7基导电荧光粉阴极射线发光增强机理研究

Currently phosphors for field emission displays (FEDs) exhibit poor luminous efficiency and degradation under excitation with lower electron voltage and higher current density electron beams. Especially, the low conductivity limits the usefulness of oxide phosphors. This project is aimed at developing novel conductive phosphors for FEDs, and the aluminates with low density, high luminous efficiency and superior stability under electron bombardment are chosen as hosts to be dopped with rare earth ions. 12CaO.7Al2O3 (C12A7) shows attractive physical and chemical properties among calcium aluminates due to its unique crystal nanocage structure, and could be converted from an insulator into a conductor by annealing in reducing atmosphere. We intend to synthesize novel C12A7/CxAy composite tricolored conductive phosphors with rare earth ions doping for FEDs by combustion method combining with heating treatment, study the mechanism of cathodoluminescence in single doped and co-doped samples, and investigate the relationship between the cathodoluminescence properties and the radiation resistance, the electrical conductivity, particle size, surface morphology and the ratio of C12A7/CxAy composites after heating treatment. Further, the dependence of cathodoluminescence properties on electron beam voltage, beam current density, type of doping ions, doping concentration, microstructure and temperature will be discussed in detail. We try to explore to obtain experimental conditions and theoretical evidence for the preparation and enhanced cathodoluminescence of novel low-voltage FEDs tricolored conductive phosphors.

本项目针对目前场发射显示器(FED)用荧光粉在低电压、大电流电子束激发下存在的转换效率低、电流饱和度差、导电性差、易于老化等关键问题，利用低密度铝酸盐为基质的稀土掺杂发光材料具有发光效率高，抗电子束轰击性能强的优点，同时依据对具有纳米带正电笼腔结构12CaO 7Al2O3(C12A7)材料在还原气氛热处理可实现导电的性质，拟通过燃烧法结合还原气氛下热处理改性制备晶粒尺寸可控的稀土离子和过渡金属离子掺杂C12A7/CxAy复合新型FED用三基色导电荧光粉材料，研究稀土离子单掺杂和共掺杂、阴极射线发光增强机理，探讨阴极射线发光与复合相组分比例、抗电子束轰击性能、晶粒尺寸、表面形貌及电导率的联系，研究阴极射线发光与电子束电压、束流密度、掺杂离子种类、浓度和还原热处理温度的依赖关系。探索今后获得新型低压FED用三基色导电荧光粉材料的实验条件和阴极射线发光增强机理。

场发射显示（FED）平板显示技术是将真空微电子管应用于显示的技术，属于低电压冷阴极发射。它兼具CRT技术亮度高、清晰度高、视角宽、工作温度范围大、响应速度快和平板显示质量轻、体积小、超薄、工作电压低（200-5000 V）、功耗小的优点，并易于拼接，可制成大屏幕显示器，成品率高，被认为是极具竞争力的新一代显示技术。本课题针对目前FED用荧光粉在低电压、大电流电子束激发下存在的转换效率低、电流饱和度差、导电性差、易于老化等关键问题，利用低密度铝酸盐为基质的稀土掺杂发光材料具有发光效率高，抗电子束轰击性能强的优点，同时依据对具有纳米带正电笼腔结构12CaO∙7Al2O3(C12A7)材料在还原气氛（氢气、CO气）热处理可通过生成困陷于笼中电子而实现导电的性质，利用自蔓延燃烧法、固态烧结等方法结合还原气氛下热处理技术制备了稀土离子掺杂单相C12A7、CxAy及混相C12A7/CxAy的蓝光、绿光、橙光、红光和白光导电荧光粉材料。通过调节稀土掺杂浓度、热处理温度和热处理气氛等条件，优化了导电荧光粉的阴极射线发光强度、发光波长、荧光寿命和电导率等性能参数；利用漫反射吸收光谱、发光动力学等光谱技术手段研究了掺杂离子种类和浓度与发光波长、发光强度、荧光寿命和电导率的关系，探讨了阴极射线发光强度与晶粒尺寸、表面形貌、电子束轰击时间、电子束电压、束流密度、掺杂离子种类、浓度和电导率的变化规律。利用吸收和拉曼光谱、电导率测量和电子自旋共振谱等技术手段研究了阴极射线发光强度与C12A7笼中电子浓度的依赖关系，探索获得了可应用于低电压、大电流电子束激发下的新型FED用导电荧光粉材料的实验条件和理论依据。