单相多波长可调硼酸盐基荧光粉的合成与发光性能调控

The project focus on the research of new single-component tunable-wavelength phosphors which can be synthesized under moderate condition for warm white LEDs. The alkaline-earth metal-zinc-borates, which have multi-cation sites with different crystal fields, are selected as the research system. In this project, the influence of different crystal field on activators, and the relation between energy transfer and tunable luminescence will be studied. The subsolidus phase relations of several alkaline-earth metal-zinc-borate ternary systems will be studied by X-ray diffraction to investigate new compounds. The compounds, having multisites with large different crystal fields, will be selected as hosts, and the photoluminescence of rare-earth cations and Mn2+ ions activated or coactivated phosphors will be studied on different activators and different doping concentrations. The energy transfer could be investigated by directly observing overlap of the excitation spectrum and the emission spectrum of two different activators. The systematically relative decline and growth of emission bands of the sensitizers and activators as well as faster decay times of energy donors will also disclose the energy transfer, and the mechanism of energy transfer from energy donors to energy acceptors will be declosed at the same time. By utilizing the principle of crystal field and energy transfer, useful single-component tunable-wavelength phosphor with high color rendering index and low color temperature will be synthesized with appropriate tuning of activator contents. Then a warm white-light-emitting will be realized for white LEDs.

研发新型单相多波长可调的荧光粉，对于制备高显色指数、低色温的暖白光LED及固态照明的发展具有重要意义。本项目拟以阳离子格位晶场差异大的碱土金属锌硼酸盐体系基质的荧光粉为研究对象，以敏化离子与激活离子间能量传递与发光性能调控为主线，从结构角度，深入研究硼酸盐基质的晶场环境对激活离子发光的影响及能量传递与发光性能之间的关系，探索合成条件温和的新型白光LED用单相多波长可调荧光粉。利用X射线衍射研究多个碱土金属锌硼酸盐体系三元系固相线下相关系，选择含有多个激活离子可占据的晶场差异较大晶格位置的化合物为基质，进行不同浓度、种类稀土离子及Mn2+离子的掺杂，深入研究基质晶场环境对激活离子发光的影响及其能量传递过程。在此基础上，通过多样化离子掺杂调控发光波长，实现单基质荧光粉的色度调节，进而获得高显色指数低色温的暖白光荧光粉，为白光LED照明提供理想材料。

为研发新型单相多波长可调荧光粉，为暖白光LED照明提供材料，本项目以阳离子格位晶场差异大的碱土金属锌硼酸盐体系基质的荧光粉为研究对象，深入研究了硼酸盐基质的晶场环境对激活离子发光的影响及能量传递与发光性能之间的关系，取得如下主要成果：.研究了过渡族金属离子Mn2+的反常发光性质及特殊制备方式。合成了第一个Mg基单掺Mn2+高强度红色荧光粉,丰富了单掺Mn2+获得高亮度荧光基质的研究种类，扩大了该类荧光材料的研究范畴，文章以内封面形式发表在Delton Transactions上。通过多种手段详细研究了α-LiZnBO3:Mn2+的局域晶场环境，发现是由于扭曲的四配位晶场导致了Mn2+离子能级劈裂，第一激发态4T1移动到更低能级，从而出现发光的红移。利用特殊的基质结构，在空气气氛下制备出低价态Mn2+激活的荧光粉，可避免高温氧化及改善热猝灭。.研究了荧光粉在高温下的相变及热稳定性的改善。α-NaSrBO3是一种优秀的基质材料，但在LED的工作温度会发生相变，转变为β-NaSrBO3。该高温相无法通过淬火稳定在室温，我们通过化学取代的方法在室温获得该高温相，并用粉末从头算法解析了其晶体结构。β-NaSrBO3:Ce3+蓝色荧光粉具有比α-NaSrBO3:Ce3+更优异的热稳定性，并用于制备了色温为3654K显色指数Ra=92.8的暖白光LED灯泡。此外，通过共掺敏化离子的方式提升了红色荧光粉SrBi2B2O7:Sm3+,Eu3+的热稳定性并通过第一性原理计算证实该方法的可行性。.研究了激活离子在具有多种阳离子格位的基质中的占位情况及局域晶场环境对离子发光的影响，并在此基础上，设计合成了单相色度可调的暖白荧光粉。

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