退火温度对酸性条件下水热合成的YVO_4荧光粉的微结构及发光特性的影响

Luminescence Property of YVO_4 Fluorescent Powders Synthesized in Hydrothermal Method

在柠檬酸三钠(Na3cit)表面活性剂辅助下利用水热法在cit3-∶Y3+摩尔比为2∶1且pH值为3条件下制备出了单分散的球形YVO4微米荧光粉,但过多cit3-基团吸附在荧光粉表面严重遮盖了YVO4晶体本身优异的性能。本论文采用退火除去吸附在荧光粉表面的cit3-基团,结果显示随着退火温度的升高(180,300,500,700,900℃),cit3-基团逐渐以CO2和水蒸汽的形式从荧光粉表面脱附,导致球形颗粒表面逐渐变得粗糙且有孔洞生成。随着cit3-基团的逐渐脱附,cit3-基团的信息逐渐消失,YVO4晶体的信息逐渐呈现。900℃下退火1 h后cit3-基团彻底脱附且YVO4晶体的结晶质量得到提高从而导致其光致发光强度达到最强。

The YVO4 fluorescent powder, with well-dispersed spherical grains in micron dimension, was synthesized in hydrothermal method. The impacts of the synthesis conditions, including the sintering temperature, type of surfactant, molar ratio of cit^3 -/Y^3 ＋, and pH value, on the microstmctures and fluorescent properties were evaluated. The YVO4fluorescent powder was characterized with X-ray diffraction, scanning electron microscopy, Raman and Fourier transform infrared spectroscopy. The results show that the annealing temperature has a major impact on the removal of cit^3- from the YVO4 grain surfaces. For examle,as the annealing temperature increased from 180℃ to 900℃, the cit^3- was completely desorbed and decomposed into CO2 and H20, accompanied by surface roughening and formation of pores. The photoluminescence of the YVO4 crystalline grains, synthesized at a pH value of 3 with a molar ratio cit^3-/Y^3 ＋ of 2： 1 and annelated at 900℃ for 60 min,were found to be the stronggest. Possible mechanisms responsible for the strong photol were tentatively discussed.