可用于白光LED的红色荧光粉NaGdTiO_4:Eu^(3+)的制备及光学性质

Synthesis and Photoluminescence of NaGdTiO_4:Eu^(3+) Red Phosphors for White LEDs

采用高温固相反应法制备了NaGdTiO4∶Eu3+红色荧光粉。利用X射线衍射和荧光光谱对NaGdTiO4∶Eu3+粉末进行了表征,研究了TiO2含量和Eu3+掺杂摩尔分数对粉末晶体结构和发光性能的影响。当TiO2的量在当量反应基础上增加50%时,制得了单一正交相NaGdTiO4。荧光光谱测试结果显示,样品在紫外区存在强的宽激发带,对应于NaGdTiO4基质的吸收。在281 nm紫外光激发下,样品显示出强的红光发射,表明NaGdTiO4基质到Eu3+之间存在有效的能量传递。该类钛酸盐红色荧光粉在近紫外光激发型白光LED中具有潜在的应用价值。

Eu3＋ -doped NaGdTiO4 red phosphors were synthesized by conventional solid state reaction method. The effects of TiO2 content and Eu^3＋ mole fraction on the crystal structure and photolumineseence properties were investigated by X-ray diffraction and fluorescent spectra. The XRD patterns showed that the resultants with single orthogonal phase structure were achieved when TiO2 content increased by 50% on the basis of stoichiometric reaction composition. In the excitation spectra of single orthogonal structure NaGdTiO4： Eu^3＋ phos- phors, by monitoring 618 nm, the charge transfer bands （CTB） of Eu^3＋-O2- and NaGdTiO4 matrix absorption centered at around 250 nm and 281 nm were observed, respectively. Under 281 nm excitation, strong red emission was observed at 618 nm originating from the ^5D0→7F2 electric dipole transition of Eu^3＋, which suggests that there exist effective energy transfer from NaGdTiO4 matrix to Eu^3＋ The calculated emission color coordinates of NaGdTiO4： 20%Eu^3＋ are x = 0.63, y = 0.34. These results show that NaGdTiO4： Eu^3＋ phosphors might have potential applications in whit light-emitting diodes （LEDs）.