溶胶-凝胶法制备Gd_(4)Ga_(2)O_(9):Dy^(3+)白光发射荧光粉及其性能

Preparation and Performance of White Light Emitting Phosphors Gd_(4)Ga_(2)O_(9):Dy^(3+)by Sol-Gel Method

通过溶胶-凝胶法制备了具有白光发射的Gd_(4)Ga_(2)O_(9):x%Dy^(3+)荧光粉,利用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)、紫外-可见漫反射光谱(UV-Vis DRS)和荧光光谱等对产物的物相结构、形貌、组分和光学性能进行研究,并分析了Dy^(3+)掺杂量对样品的影响。XRD结果表明,所制备的样品为Dy^(3+)掺杂的Gd_(4)Ga_(2)O_(9)单斜晶体和少量Ga_(2)O_(3)杂质相的混合物。紫外-可见漫反射光谱结果表明制备的Dy^(3+)掺杂Gd_(4)Ga_(2)O_(9)晶体是一种光学带隙为5.29 eV的直接带隙半导体。荧光检测结果表明Dy^(3+)掺杂Gd_(4)Ga_(2)O_(9)荧光粉可被属于Gd^(3+)激发带的275 nm紫外光有效激发,并在490 nm和575 nm附近分别发射出属于Dy^(3+)的^(4)F_(9/2)→^(6)H_(15/2)和^(4)F_(9/2)→^(6)H_(13/2)跃迁的蓝色和黄色的强烈光,证实在Gd_(4)Ga_(2)O_(9):Dy^(3+)样品中存在显著的由Gd^(3+)到Dy^(3+)的能量传递发光现象。同时,对其发光机制进行了讨论。样品的发光强度随着Dy^(3+)掺杂量的变化而变化,同时影响着样品的发光颜色,Dy^(3+)掺杂量为1.5%和2%时制备的荧光粉可在紫外光激发下分别发射出CIE色坐标为(0.3362,0.3512)和(0.3381,0.3523)、相关色温为5340 K和5263 K的白色光。研究结果表明Gd_(4)Ga_(2)O_(9):Dy^(3+)是一种潜在的紫外光激发白光发射荧光材料。

Gd_(4)Ga_(2)O_(9):x%Dy^(3+)phosphors with white light emission were prepared by sol-gel method.The phase structure,morphology,composition and optical properties of the samples were studied by X-ray powder diffraction(XRD),scanning electron microscope(SEM),energy dispersive X-ray spectrometry(EDS),UV-Vis diffuse reflectance spectroscopy(UV-Vis DRS),and photoluminescence spectroscopy(PL).The XRD results show that the samples are mixtures of Dy^(3+)doped Gd_(4)Ga_(2)O_(9) monoclinic crystals and a slight impurity phase corresponding to Ga_(2)O_(3).The results of UV-Vis DRS indicate that the Dy^(3+)doped Gd_(4)Ga_(2)O_(9) crystal is a direct semiconductor with an optical band gap of 5.29 eV.The PL results reveal that the Dy^(3+)doped Gd_(4)Ga_(2)O_(9) phosphors can be effectively excited by an excitation band of Gd 3+at 275 nm,and emit intense blue and yellow light at 490 nm and 575 nm,which attribute to the ^(4)F_(9/2)→^(6)H_(15/2) and ^(4)F_(9/2)→^(6)H_(13/2) transitions of Dy^(3+),respectively,confirming that there is an obvious energy transfer luminescence phenomenon from Gd^(3+)to Dy^(3+)in Gd_(4)Ga_(2)O_(9):Dy^(3+)samples.The possible luminescence mechanism of Gd_(4)Ga_(2)O_(9):Dy^(3+)phosphors was briefly proposed.The luminous intensity of the sample varies with the doping amount of Dy^(3+),which also affects the luminous color of the prepared product.The Gd_(4)Ga_(2)O_(9):1.5%Dy^(3+)and Gd_(4)Ga_(2)O_(9):2.0%Dy^(3+)phosphors can emit white light with CIE color coordinates of(0.3362,0.3512)and(0.3381,0.3523)and correlated color temperatures of 5340 K and 5263 K under the excitation of ultraviolet light,respectively.The results imply that Gd_(4)Ga_(2)O_(9):Dy^(3+)is a potential white light emitting luminescence mate-rial excited by ultraviolet light.