Ce^(3+)激活的焦硅酸钆钠荧光粉的VUV-VIS发光特性

Luminescence of Ce^(3+) ion Activated Sodium Gadolinium Pyrosilicates Phosphor under Vacuum Ultraviolet-Vis Excitation

高温固相法合成了Na3Gd1-xCexSi2O7系列荧光粉。利用Na3LuSi2O7结构模型,通过Rietveld方法精修了Na3GdSi2O7晶体结构,结果表明,Na3GdSi2O7属于六方晶系,P63/m点群,晶格参数a=b=947.79(1)pm,c=1387.48(3)pm,c/a=1.4639。Na3GdSi2O7体系中存在Gd3+(1)和Gd3+(2)两个格位。Gd3+(1)离子位于Wyck.4f格位,为扭曲八面体结构。Gd3+(2)离子位于Wyck.2a格位,具有正三棱柱构型。进一步考察了Na3Gd1-xCexSi2O7荧光粉的真空紫外-紫外-可见发光光谱,讨论并指认了Ce3+在上述两个格位中的激发带位置及能级重心。发射光谱曲线分别由两个～400 nm和～508 nm宽带发射构成,随着Ce3+浓度增加,短波～400 nm发射逐渐增强。

The Ce3＋ doped sodium gadolinium pyrosilicates Na3Gd1-xCexSi2O7 phosphors were prepared through a high-temperature solid-state reaction technique.The crystal structure of Na3GdSi2O7 was refined by Rietveld method with Na3LuSi2O7 structure model.The results showed that the compound Na3GdSi2O7 crystallized in a hexagonal system（P63/m） with lattice parameters a=b=947.79（1） pm,c=1387.48（3） pm and c/a=1.4639.There were two Gd3＋ lattice sites in Na3GdSi2O7,denoted Gd（1）3＋ and Gd（2）3＋.The Gd（1）3＋ ions at Wyck.4f sites were with 6-fold distorted octahedron coordination（trigonal antiprism tap）,and Gd（2）3＋ ions at Wyck.2a sites were with 6-fold regular trigonal prism coordination（tp）.The VUV-VIS luminescence properties of phosphors Na3Gd1-xCexSi2O7 were investigated,and the origin of these 4f-5d excitation bands and the 5d centroid of Ce3＋ in two sites were assigned and discussed.The emission spectra of phosphors Na3Gd1-xCexSi2O7 were composed of broad band at ~400 and ~508 nm,respectively,and the relative intensity of Ce3＋ emission at ~400 nm increased with the increasing of Ce3＋ concentration.