Li Zhenling, Wang Zhijun, Li Panlai, Cheng Jinge, Tian Miaomiao, Wang Chao, Yang Zhiping
College of Physics Science & Technology, Hebei Key Lab of Optic-Electronic Information and Materials, Hebei University, Baoding 071002, China. +
Dalton Trans. 2017 Oct 24;46(41):14310-14317. doi: 10.1039/c7dt02916k.
Blue emitting phosphor is urgently needed in commercial application of white light emitting diodes for the reason that the existing ones lack proper emission and have poor thermal stability. Herein, we report two methods for SrCaAlSiO:Eu phosphors that were performed to optimize the luminescence properties and thermal stability based on structural reconstruction. One is partial substitution of Al-Sr by Si-Na forming SrNaCaAlSiO:0.03Eu (x = 0-0.7); the other is altering the proportion of Ca and Sr, forming SrCaAlSiO:0.03Eu (y = 0-0.97) solid solution. The phosphor's structural evolution, variation of the Eu local environment, luminescence and thermal quenching were explored in detail. As a result, for SrNaCaAlSiO:0.03Eu (x = 0-0.7) series, (Al/Si)O tetrahedrons are enlarged and Eu-O polyhedrons are compressed; the emission gets red-shifted from 418 nm to 428 nm under 350 nm excitation; the thermostability of SrCaAlSiO:0.03Eu is improved with the incorporation of Si-Na pair. For SrCaAlSiO:0.03Eu (y = 0-0.97) series, the emission peak shows a large shift from 420 nm to 440 nm, which is attributed to a comprehensive result of nephelauxetic effect and crystal field splitting. Furthermore, thermal stability is improved by the coexistence of Ca and Sr. White light emitting diodes fabricated by combining the as-prepared phosphor with commercial phosphors exhibit an excellent color rendering index R of 90.1 and a temperature of 4459 K with CIE coordinates of (0.357, 0.356). These results indicate that the as-developed composition series are promising for commercial application.
由于现有的蓝色发光磷光体缺乏适当的发射且热稳定性较差，因此在白光发光二极管的商业应用中迫切需要这种磷光体。在此，我们报告了两种用于SrCaAlSiO:Eu磷光体的方法，这些方法基于结构重构来优化发光性能和热稳定性。一种是用Si-Na部分取代Al-Sr，形成SrNaCaAlSiO:0.03Eu（x = 0-0.7）；另一种是改变Ca和Sr的比例，形成SrCaAlSiO:0.03Eu（y = 0-0.97）固溶体。详细研究了磷光体的结构演变、Eu局部环境的变化、发光和热猝灭。结果表明，对于SrNaCaAlSiO:0.03Eu（x = 0-0.7）系列，（Al/Si）O四面体增大，Eu-O多面体被压缩；在350nm激发下，发射从418nm红移至428nm；随着Si-Na对的引入，SrCaAlSiO:0.03Eu的热稳定性得到提高。对于SrCaAlSiO:0.03Eu（y = 0-0.97）系列，发射峰从420nm大幅移至440nm，这归因于协同效应和晶体场分裂的综合结果。此外，Ca和Sr的共存提高了热稳定性。将制备的磷光体与商用磷光体结合制成的白光发光二极管具有出色的显色指数R为90.1，色温为4459K，CIE坐标为（0.357, 0.356）。这些结果表明，所开发的组成系列在商业应用中具有前景。
