采用共烧结法制备了硼硅基质Ce:YAG荧光玻璃,研究了烧结温度在600℃~900℃范围内,Ce:YAG荧光玻璃的发光强度变化和色坐标漂移规律.结果表明,随着烧结温度的升高,Ce:YAG荧光玻璃发光强度先增强后减弱,700℃烧结时,荧光玻璃获得最大发光强度;超过850℃烧结时,荧光玻璃无发光性能;同时,色坐标(x,y)发生漂移,且比相同烧结温度的荧光粉漂移幅度大.通过X射线粉末衍射仪、差示扫描量热分析仪和X射线光电子能谱分析仪测试分析表明:随着烧结温度升高,荧光粉中的Ce3+被玻璃基质氧化成Ce4+,玻璃液体腐蚀破坏了荧光粉YAG晶体结构,降低了荧光玻璃的发光强度,从而导致色坐标劣化漂移.
The color conversion glass is a promising material for light emitting diodes encapsulation due to its high thermal conductivity and good thermal stability. In present study, color conversion glasses were prepared by sintering a mixture of borosilicate glass frits and a YAG phosphor at temperature from 600℃ to 900℃. The effects of sintering temperature on luminescence properties were examined. Characteristics of color conversion glasses, with respect to luminescence intensity, CIE (Commission International de I'Eclairage) chromaticity and CCT (Correlated Color Tem-perature) were analyzed based on luminescence excitation and emission spectra. These characteristics are dependent on sintering temperature of the color conversion glasses. The CIE coordinates shift with increase of sintering tempera-ture. The glass, sintered at 700℃, shows the best luminescence properties. But for the glasses sintered above 850℃, their luminescence properties may be destroyed. Test results of X-ray diffraction (XRD), differential scanning calo-rimetry (DSC) and X-ray photoelectron spectroscopy (XPS) reveal that degradation of luminescence properties with increase of sintering temperature is ascribed to the lattice disturbance of YAG and oxidation of Ce3+, which is causedby reactions between glass matrix and YAG phosphors. The present study may promote the application of color conversion glasses in light emitting diodes encapsulation.
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