溶胶-凝胶法制备小颗粒(Y,Gd)BO_3∶Eu及其表征

Preparation of Small-sized (Y,Gd)BO_3∶Eu Phosphors by Sol-gel Process and Their Characterization

用溶胶 凝胶方法制备了平均粒径为 1～ 2 μm的小颗粒、高发射效率的 (Y ,Gd)BO3 ∶Eu红色发射荧光体。用XRD、SEM、粒度分析和PL光谱对荧光体作了表征和研究。常规固相反应合成 (Y ,Gd)BO3 ∶Eu需在 1 2 0 0℃以上才能形成均一的固溶体。而溶胶 凝胶法制取稀土正硼酸盐 80 0℃灼烧已可形成均一的单相 (Y ,Gd)BO3 ∶Eu,在 1 1 0 0℃可得到发光亮度最高的荧光体。它的亮度是常规固相反应于 1 2 0 0℃制得的荧光体的 1 2 0 %。采用溶胶 凝胶法制取 (Y ,Gd)BO3 ∶Eu荧光体 ,可在相当宽的实验条件范围内得到小粒径、窄分布和高亮度的荧光体 ,且有良好的颗粒形貌。

Red emitting phosphors (Y, Gd)BO_3∶Eu, with mean size of 1～2 μm were prepared by a sol-gel process combined with a furnace firing. For the sol-gel procedure, tri-n-butyl borate B(OC_4H_9)_3 was mixed and stirred with a nitric solution of Y_2O_3, Gd_2O_3, Eu_2O_3 having a mole proportion of 0 45∶0 50∶0 05 in ethanol. The (Y, Gd, Eu)BO_3 gel precursor prepared from solution was sintered at a certain temperature range of 800～1 200 ℃. The prepared orthoborates were characterized with X-ray diffraction, scanning electron microscopy and photoluminescence. Conventional solid state reactions require higher sintering temperatures above 1 200 ℃ for pure (Y, Gd)BO_3∶Eu phase. However, the sol-gel process allows a significant decrease of the sintering temperature and the phosphor sintered at 800 ℃ had pure orthoborate phase. The effect of preparation conditions such as amount of B(OC_4H_9)_3 and sintering temperature on the crystallinity, morphology and luminescence characteristics of phosphor particles were investigated. The results show that 10%～20% excess of B(OC_4H_9)_3 is favorable to get pure orthoborate phase and control the morphology of particles. Also, the particle size and VUV luminescence of phosphors are dependent on sintering temperature. The particles obtained by sintering at 1 000 and 1 100 ℃ had narrow distribution and the aggregation of particles appeared at 1 200 ℃. The PL intensity of the phosphor prepared by sol-gel process reached the maximum value at 1 100 ℃ and was 20% higher than that of the phosphor prepared at 1 200 ℃ by conventional solid state reaction. By sol-gel process, small-sized (Y, Gd)BO_3∶Eu with narrow distribution, high luminescent efficiency and good morphology can be prepared in a wide range of reaction condition.