近紫外荧光粉SrAl_2Si_2O_8∶Ce~(3+)的光致发光特性

采用高温固相反应法制备了xCe~(3+)(x=0.01%,0.05%,0.10%和0.30%)激活的Sr_(1-x)Al_2Si_2O_8近紫外荧光粉,利用X射线衍射(XRD)和扫描电镜(SEM)检测出荧光粉的物相结构,通过光致发光谱(PL)和激发光谱(PLE)表征了荧光粉的发光性质。结果显示,在中波紫外光激发下,发射峰位于长波紫外区,归属于Ce~(3+)的5d→2 F5/2和5d→2 F7/2跃迁。激发波长308nm时,观察到近紫外SrAl_2Si_2O_8荧光粉的发光强度随Ce~(3+)掺杂量增加而先增大后减小,同时发射峰位置红移。280和325nm波长选择性激发条件下的差异性发射行为表明SrAl_2Si_2O_8∶Ce~(3+)具有两种性质不同的发光中心,该结论由监测320和390nm发射时获得的形状具有明显区别的激发光谱亦可得以验证。离子半径的匹配性支持Ce~(3+)优先取代Sr~(2+),同时Van Uitert的经验公式估算结果推断出低浓度的Ce~(3+)生成九配位的Ce(Ⅰ)发光中心,高浓度掺杂情况下部分相互近邻的Ce~(3+)有效配位数减小,形成八配位的Ce(Ⅱ)发光中心。紫外280nm激发下峰位348nm的发射谱带源于Ce(Ⅰ)和Ce(Ⅱ)发光中心共同贡献,紫外325nm激发下发射峰位于378nm的发射带则主要对应于Ce(Ⅱ)发光中心。紫外光激发下Ce~(3+)发射出较强的近紫外光,表明SrAl_2Si_2O_8∶Ce~(3+)是一种适用于研发紫外荧光光源的荧光粉体材料。

Photoluminescence Properties of Near-Ultraviolet SrAl2 Si2 O8 :Ce3+Phosphors

Near-ultraviolet phosphors SrAl2 Si2 O8 :xCe3 + (x =0.01,0.05％,0.10％ and 0.30％)were synthesized with high temperature solid state method.X-ray diffraction (XRD)and scanning electron microscope (SEM)were used to reflect crystal phase structure,and the luminescent properties of fluorescent powder were characterized with emission spectrum (PL)and exci-tation spectrum (PLE).Under ultraviolet-B (UVB)irradiation excitation,wide emission bands were observed in ultraviolet-A (UVA)region,which were assigned to the 5d →2 F 5/2 and 5d →2 F 7/2 transitions of Ce3 + .Along with a redshift of the emission peak about 23nm,the luminescence intensity of SrAl2 Si2 O8 phosphor increased first and then decreased,when Ce3 + doping con-tents had been increased.The diversity of emission behavior under selected 280 and 325 nm excitation shows that SrAl2 Si2 O8 :Ce3 + have luminescence centers with two different natures,and that was further confirmed by the obviously distinct excitation spectral shapes of 320 and 390 nm emissions.Ce3 + gives priority to instead Sr2+ owing to the compatibility of ionic radius,and the crystallograhic sites are deduced by Van Uitert formula.The results indicate that Ce(Ⅰ)luminescence center originates from nine coordination of the Ce3 + ions in low concentration doping,and Ce(Ⅱ)center is due to the fact that effective coordination numbers of partial Ce3 + decrease to 8 in high concentration doping cases.The emission bands centered at 348 nm under 280 nm excitation are derived from the cooperation of both Ce(Ⅰ)and Ce(Ⅱ),and that located at 378 nm under 325 nm excitation are mainly attributed to Ce(Ⅱ).Strong near-ultraviolet fluorescence of Ce3 + under ultraviolet excitation reveals that SrAl2 Si2 O8 :Ce3 + phosphors are one potential material suitable for developing UV fluorescent light source.