暖白光LED用低光衰高显色性Lu3Al5-x(Si/B)xO12-yNy:Ce荧光粉的研究

The emission colors of LuAG:Ce consisting of the similar crystal structure with YAG:Ce can be tailored through the substitution of ions to control its microstructure. Moreover, the luminescent efficiency and thermal stability of the synthesized novel Lu3Al5-x(Si/B)xO12-yNy:Ce phosphors are much better than those of YAG-based oxynitride phosphors, which has a potential application on warm white LEDs with a low correlated color temperature (CCT) and a high color-rendering index (CRI). However, little attention has been paid on investigating the modification of optical properties of LuAG:Ce by controlling the microstructure. Also it is still unknown that why the optical properties of Lu3Al5-x(Si/B)xO12-yNy:Ce phosphors are largely improved. In this project, novel Lu3Al5-x(Si/B)xO12-yNy:Ce phosphors will be synthesized by the incorporation of N3? into the LuAG host to change its microstructure. The occupied site of substitution ions in LuAG host and the local microstructural variation around activators will be carefully investigated and simulated by HAADF-STEM, EXAFS, XANES, neutron diffraction and the first principles,respectively. By investigating the effect of chemical composition variation and preparation process on lattice structure and optical properties, the relationship and interaction mechanism of the chemical composition, crystal structure and luminescence property will be disclosed, and the luminescent mechanism will be illuminated. Finally, the optical properties of LuAG:Ce phosphors can be efficiently designed and tailored by the replacement of ions. The present work will lay the foundation for developing warm-white LEDs with high luminescent efficiency, a high CRI and a low CCT.

通过离子取代进行微结构调控合成的新型Lu3Al5-x(Si/B)xO12-yNy:Ce荧光粉，不但发射色彩可控裁剪，且光效和热稳定性都远远优于同结构的YAG:Ce材料，在低色温和高显色性暖白光LED中表现出巨大应用潜力，但其发光性能提高的内在机制尚不清楚。本项目以新型Lu3Al5-x(Si/B)xO12-yNy:Ce荧光粉为研究对象，综合利用微观结构分析和第一性原理的模拟计算，研究取代离子占据LuAG晶格的具体位置及取代后发光离子中心的局部微结构变化；通过化学组成设计、制备工艺优化、精细结构解析和发光性能的系统研究，揭示其相互之间的关系，阐明其发光机制，深化对晶态材料宏观发光特性与发光中心微观功能基元本质的认识，进而提出实现微结构调控新型Lu3Al5-x(Si/B)xO12-yNy:Ce荧光体发光性能剪裁设计和可控制备的有效途径，为研制低色温和高显色指数的暖白光LED奠定基础。

与商业化白光LED中常用的YAG:Ce荧光粉相比，LuAG作为荧光粉基质材料具有更为明显的优势和更加优异的性能，因此，LuAG:Ce作为荧光粉材料在白光LED器件上的应用研究及其发光性能提高的机理应该重新引起研究者们的高度重视。 基于此，本研究项目以离子取代进行微结构调控的新型Lu3Al5-x(Si/B)xO12-yNy:Ce荧光体为研究对象，以成本低廉的高纯度氧化物、亚微米α-Si3N4、纳米无定形Si3N4、BN、AlN及烧结助剂为原料，通过高温固相烧结工艺在LuAG晶格中引入不同形式的N3-离子进行微结构调控，制备了不同N3-离子固溶度的Lu3Al5-x(Si/B)xO12-yNy:Ce荧光材料；研究了N3-离子的不同引入方式、固溶度、助溶剂、温度、保温时间等因素对荧光粉精细结构、光学帯隙、发光性能的影响及其内在作用机制，探讨了Lu3Al5O12-xNx:Ce荧光体发光强度增强的根本原因；研究了不同化学组成荧光材料的高温荧光特性，阐明了新型石榴石基氧氮化物荧光体的发光动力学和发光机制。在此基础上，通过其化学组成设计、制备工艺的优化和精确控制，实现了微结构调控新型Lu3Al5-x(Si/B)xO12-yNy:Ce荧光体发光性能的有效剪裁设计和可控制备，并探索了其在高发光效率、低色温和高显色性暖白光LED上的应用潜能。