YAG∶Ce发光材料合成的助熔剂研究

Effect of Flux on YAG∶Ce Phosphors Prepared by Solid-state Reactions

采用高温固相法合成YAG：Ce荧光粉时，传统的以硼酸为助熔剂的产物硬度很大，处理过程中容易破坏晶体形貌，影响发光性能。采用氟化物助熔剂（MgF2、CaF2、SrF2、BaF2、AlF3）及它们与H3BO3混合助熔剂来制备YAG：Ce，研究了助熔剂种类及其浓度对制得的粉体发光性能的影响，比较了它们的晶体形貌与物相组成。结果表明，采用不同助熔剂合成的YAG：Ce的激发光谱及发射光谱基本相同，而BaF2、AlF3、SrF2及它们与H3BO3的混合助熔剂系列，可在一定程度上降低产品硬度、提高产品发光亮度；其中H3BO3-SrF2系列、H3BO3～BaF2系列的晶化程度与粒度分布均有改善；H3BO3～BaF2系列的物相组成比较纯，除Y3Al5O12：主相外基本无杂相。

When preparing phosphor yttrium aluminum garnet Y3Al5O12 （YAG） activated with cerium （Ce^3＋） by solid-state reactions, the fluxes addition has great influence on the ion diffusions, crystallization process as well as on the formation of YAG matrix with good crystaUinity. As a result, the crystallite size distribution and luminous efficacy of the phosphor as well as the hardness of the product are closely relative to the flux applied. It is known that the YAG： Ce phosphor prepared by solid-state reaction using H3BO3 as a flux often exhibited high hardness, causing many troubles in post-treatment. In this paper, YAG： Ce phosphors with the same Y/Al atomic ratio and the same atomic fraction of Ce were synthesized using different fluxes including a series of fluorides fluxes （such as MgF2, CaF2, SrF2, BaF2, AlF3 ） and mixed fluxes of fluorides with H3BO3. Effect of types and concentrations of the flux on the morphology, crystallite and luminescent properties of YAG： Ce were studied. It was found that the phosphors prepared with the fluxes studied in this work exhibited typical crystal structure of garnet and no impurity phase was detected. The excitation and emission spectra of the phosphors with different fluxes were roughly same. The main differences of the phosphors prepared with different fluxes were the hardness and luminescent brightness of the products. The luminescent brightness was higher while the hardness was lower for the YAG： Ce phosphor prepared with BaF2, AlF3, SrF2 and their mixture with H3BO3 compared with that using H3BO3 as flux alone. It is supposed that from the practical application point of view, BaF2, AlF3, SrF2 and their mixture with H3BO3 were the better fluxes for YAG： Ce among all fluxes investigated.