白光LED用橙红色荧光体Sr_2MgSi_3O_9:Eu^(3+)的制备和光谱性质

Preparation of Orange-red Emitting Phosphors Sr_2MgSi_3O_9:Eu^(3+) for White LEDs and Its Photoluminescent Properties

采用凝胶-燃烧法在活性炭弱还原气氛下成功合成了新型橙红色发光材料Sr2MgSi3O9:Eu3+.用X射线粉末衍射仪(XRD)、扫描电镜(SEM)、荧光分光光度计等对合成产物进行了分析和表征.结果表明:此发光材料与Sr2MgSi2O7具有相似的晶体结构,同属四方晶系.样品的一次颗粒近似球形,粒径在100 nm左右.样品Sr2MgSi3O9:Eu3+的激发光谱在220~300 nm内出现一宽带吸收,归属于Eu3+-O2-之间的电荷迁移带,300 nm以后出现的锐线峰为Eu3+的f→f跃迁吸收峰,其最强锐线峰位于400 nm,对应于Eu3+的基态到5L6激发态跃迁吸收,因而,可以被InGaN管芯产生的紫外辐射有效激发.发射光谱由2个强发射峰组成,位于592 nm和618 nm处,分别属于典型的Eu3+的5D0→7F1和5D0→7F2跃迁.此外,研究还发现共掺杂适量Ti使得发光颜色由橙红色向红色转变,发光强度明显增强.

Novel phosphors Sr2MgSi3O9：Eu^3＋ synthesized by gel-combustion method in weak reductive environment.The as-synthesized phosphors were investigated by XRD,SEM and Fluorescence spectrophotometer.The results show that Sr2MgSi3O9： Eu^3＋ phosphor possesses the similar tetragonal crystal structure as that of Sr2MgSi2O7.The initial particles of as-synthesized phosphors are nearly spherical in shape,and the particle size is about 100 nm in diameter.The excitation spectrum of Sr2MgSi3O9：Eu^3＋ sample presents wide band absorption between 220300 nm,which is ascribed to the charge transfer between Eu^3＋-O^2-.The sharp peaks after 300 nm belong to f→f transition of Eu^3＋,and the strongest sharp peak is located at 400 nm,which is ascribed to the transition from the ground state of Eu^3＋ to 5L6 excited state.Therefore,samples can be efficiently excited by ultraviolet radiation from InGaN chip.The emission spectrum consists of two emission peaks at 592 nm and 618 nm,which are ascribed to ^5D0→^7F1 and ^5D0→^7F2 respectively.Moreover,it is found that co-doped Ti^4＋ with the proper content can make the emitting colour shift from orange-red to red,and improve intensity of luminescence effectively.