复合基团单相白光荧光粉的双温区Al还原制备及光谱调控

The uses of single-phased white-light-emitting phosphors provide an optimum solution for the realization of high-power light-emitting didoes (LED) due to their stable photoluminescence properties. In this project, "co-host" design concept will be used to design and exploring novel and high photoluminescence performance phosphors. Their photoluminescence prosperities will be improved through the synergistic effect among the composed groups. Furthermore, the crystal building process as well as the group synergistic effect mechanism will be investigated and expounded. Novel and effective aluminum reduction method will be simultaneously used for the phosphors preparation. Different from the traditional reduction methods (Carbon thermal reduction or H2/N2 reduction method), aluminum reduction method allowed us achieving the reduction reaction in a wide and effective temperature range, and at the same time avoiding the pollution problems as in the carbon thermal reduction. By controlling the reductive level, the emission centers can be coexisted in a mixed valence state, spectra control will be thereby achieved and a white light emitting will be finally obtained. The coexisting valence state of different the emission centers and the group synergistic effect in the phosphors prepared by the aluminum reduction method will be investigated in detail in this project. The achievements of this project will provide a new method for phosphors spectra control, and also bring us new inspire to design excellent phosphors for high-power LED application.

单相白光发射荧光粉因其稳定的发光性能成为面向大功率白光LED应用的较优的发光材料。荧光粉基质材料的设计一直是开发优质荧光粉关键。本项目拟使用"复合基团"概念进行单相白光发射荧光粉的设计与合成，通过基团间的协同效应改善荧光粉的发光性能，并深入研究复合基团对于基质材料晶体场环境构建的影响及基团间协同效应的内在机理。与传统荧光粉的碳热还原法和氮氢还原法不同，本课题在优选复合基团单相白光荧光粉基质的基础上，采用双温区Al还原法对荧光粉进行原位还原，既能避免类似于碳热还原时产生还原剂污染的问题，也能在广泛的温度区间实现还原反应。通过控制还原程度使荧光粉的发光中心处于混合价态，以实现对荧光粉的光谱调控并混色发出白光。本项目将着重深入研究Al还原条件下发光中心的价态以及基团间的协同效应等科学问题。项目的实现将为大功率LED用单相白光发射荧光粉设计开发及荧光粉的光谱调控提供新的思路及科学依据。

本项目突破传统荧光粉的设计理念和还原技术限制，基于Al还原制备手段，实现复合基团单相白光发射荧光粉的设计合成及光谱调控。围绕研究内容，发表SCI论文24篇，其中1区期刊7篇，IF>10期刊论文1篇，IF>5期刊论文4篇；申请国家发明专利53项，其中授权专利14篇；获上海市技术发明奖二等奖等省部级奖项3项。主要研究内容如下：.1．设计合成了Ca11(SiO4)4(BO3)2:Ce3+,Tb3+,Mn2+复合基团单相白光发射荧光粉，通过[SiO44-]与[BO33-]基团的协同效应，使荧光粉具备了很好的色彩平衡能力，通过掺杂中心浓度优化，基于发光中心能量传递，调控出色坐标位于(0.303, 0.309)的白光发射，将荧光粉与匹配的365nm紫外芯片封装成白光LED，光源显色指数达92.2。.2．设计合成了Na5Y4(SiO4)4F:Eu2+,Tb3+,Eu3+氧氟基复合基团单相白光发射荧光粉中。通过在基质材料中单掺Eu3+离子实现发射增强，验证了F-离子基团的电负性属性对基质晶体场环境的影响作用，制备出高效Eu3+掺杂的红光荧光粉。通过Eu2+,Tb3+,Eu3+共掺，制备出色坐标位于(0.407, 0.373)的白光发射荧光粉。深入研究了荧光粉中离子混合价态的存在机理，及荧光粉中发光中心间的能量传递过程。.3．设计合成了Eu3+单掺的Ca8(Al12O24)(MoO4)2复合基团单相白光发射荧光粉，深入研究了基团间的协同效应对荧光粉发光性能的影响，得益于[MoO4]和[Al12O24]的协同作用，使得Eu3+离子的红光发射与Mo-O基团的蓝绿光发射到了很好的平衡，最终在单掺杂Eu3+离子的情况下实现了色坐标位于(0.3398, 0.3396)白光发射。.4．揭示了Al还原反应实现荧光粉还原制备及光谱调控的作用机理。Al还原通过抽取阳离子配位氧的方式，在结构中制造了氧空位，从而实现了发光中心的还原及晶体场调控，并籍此实现了荧光粉的白光调控。同时掌握了Al还原实现荧光粉还原制备的工艺参数;Al还原可以在500-1000℃的广泛温度区间内对目标荧光粉进行还原制备；可实现10min的超快还原反应，是一种高效、节能、绿色的普适性的还原反应手段。