基于笼形微球增强吸收和铝基包覆抑制猝灭的激光照明玻璃陶瓷

Pending a solution to LED efficiency droop, solid state lighting by phosphor converted laser diodes (LD) has been becoming one international research hotspot. One of the most prospective phosphors is luminescent multi-crystalline-phase glass-ceramics with different diverse bands, but it is being held backed by two challenges. One is how to conquer laser saturation effects to enhance absorption; the other is how to effectively avoid luminescent quenching by impurities and thermal effects. Based on such backgrounds, we proposed to develop a series of glass-ceramics with involved luminescently yellow YAG: Ce3+ and red CaAlSiN3: Eu2+ cage-like microspheres as well as borosilicate low Tg glasses so as to realize high absorption, efficiencies, saturation power critical values and thermal conductivities of materials. 1) In order to solve the problem deriving from laser saturated absorption, the cage like microstructures with interconnected pores is proposed to suppress scattered loss of incident light. And large specific surface area of the cage-like micro-sphere is also good to get enhanced absorption. 2) In order to maintain the high quantum efficiencies of the luminescent phases, a AlN or A2O3 protection layer is proposed to coating for YAG: Ce3+ and red CaAlSiN3: Eu2+ phases, respectively. This strategy is effectually to avoid the corruption crystalline phase or the introduction of impurities from the concentration gradient driven diffusion. That is also actually favorable to improve heat dissipation and constrict thermal quenching owing to the high thermal conductivity of AlN or A2O3. Hence, the luminescent quenching problems led by impurities and thermal effects will be well resolved.

由于激光照明技术可克服大功率LED照明的效率衰退问题,因此近来成为国内外研究热点。含有多荧光功能相的玻璃陶瓷是重要研究方向之一,但亟需解决阻碍吸收增强的激光饱和吸收难题和阻碍光效提高的杂质猝灭与热猝灭难题。为此,本项目拟采用具有笼形结构的黄色YAG:Ce3+、红色CaAlSiN3:Eu2+荧光微球和低熔点玻璃,经低温共烧构建一类高吸收、高光效、高激光饱和激发功率、高热导的激光照明玻璃陶瓷。1) 利用笼形结构多孔通道的陷光效应来抑制散射损失,同时利用笼形结构的大比表面积来增强吸收,以此解决饱和吸收难题。2)为了保持荧光功能相的高发光效率,在CaAlSiN3:Eu2+和YAG:Ce3+荧光功能相表面分别包覆一层AlN或 A2O3保护层。这不仅可避免烧结过程由浓度梯度驱动的互扩散破坏功能相或引入杂质缺陷,还可利用AlN和A2O3的高热导来改善散热、降低热猝灭,有望同时解决杂质猝灭和热猝灭问题。

由于激光照明技术可克服大功率LED照明的效率衰退问题,因此近来成为国内外研究热点。含有多荧光功能相的玻璃陶瓷是重要研究方向之一,但亟需解决阻碍光吸收增强难题和发光猝灭难题。为此,本项目研制了具有笼型结构的黄色YAG:Ce3+荧光微球和红色Mg2Al4Si5O18: Eu2+荧光微球，经与低熔点磷酸盐玻璃低温共烧获得了一类高效激光照明玻璃陶瓷。主要获得了以下重要结果：.（1）研制了一种Al2O3包覆黄色YAG: Ce3+笼形荧光微球和一种Al2O3包覆红色Mg2Al4Si5O18: Eu2+笼形荧光微球，二者在蓝光波段（440nm~470nm峰位）均具有特征吸收，且分别在黄光波段（540 nm峰位）和红光波段（610nm峰位）具有高效（IQE>50%）、宽谱(FWHM>50nm)发光。.（2）研制了一类软化温度低(<500℃)的氟磷酸盐低熔点玻璃，与YAG: Ce3+和Mg2Al4Si5O18: Eu2+荧光微球在玻璃软化点以上（>550℃）不发生反应，且具有良好的抗激光辐照损伤性能，因此能够作为低温粘结相与上述两种荧光粉复合成荧光玻璃陶瓷。.（3）研制了一类均匀含有黄色YAG: Ce3+笼形荧光微球和红色Mg2Al4Si5O18: Eu2+笼形荧光微球的荧光玻璃陶瓷，具有良好的化学稳定性和较高的热导率（1.42 W/(mK)），在蓝光LD激发下具有高的激光激发饱和功率密度（3.3 W/mm2）和高的发光效率。.（4）采用具有笼形结构的黄色YAG:Ce3+、红色Mg2Al4Si5O18: Eu2+荧光微球复合荧光玻璃陶瓷和蓝光LD试制了激光照明器件，获得了高达153.0 lm/W的流明效率、色温为3898K、显色指数为82，优于两个对比实验的LD器件性能。.因此，本项目成果可为研发高饱和激发功率、高效、高显色指数和高温稳定的新型激光照明器件提供新的材料基础，具有重要的材料科学研究意义和工程应用价值。