采用微乳液-水热法合成一系列NaLa(MoO4)2∶Eu3+/Tb3+/Tm3+单/共掺的荧光粉(NLM)。 采用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 荧光光谱对荧光粉的晶体结构、 形貌特征和发光性质进行了测试和研究。 结果表明: 所制备的样品均为四方晶系单晶, Eu3+, Tb3+, Tm3+均以取代的方式进入La3+的格位; 样品的形貌为四方片状结构, 颗粒尺寸1～1.5 μm; 当Eu3+掺杂浓度为是9%时, NLM∶9%Eu3+荧光粉在616 nm发射峰是最强的, 此时在NLM基质中Eu3+之间的临界传递距离(Rc)约为15.20 。 在NLM∶9%Eu3+的发射光谱中, 591 nm处的发射峰为Eu3+的5D0→7F1的磁偶极跃迁; 616 nm处的发射峰为Eu3+的5D0→7F2的电偶极跃迁, 电偶极跃迁发射强度约是磁偶极跃迁强度的10倍, 表明Eu3+位于无反演对称中心格位。 采用固定Eu3+(Tb3+)的浓度, 改变Tb3+ (Eu3+)浓度的方法, 研究了Eu3+与Tb3+之间的能量传递机理。 通过调节Eu3+, Tb3+和Tm3+的掺杂浓度, 实现在单一基质条件下可见光区域的光色调节, 在360 nm激发下NLM∶x%Eu3+, y%Tb3+, z%Tm3+荧光粉的发光由蓝光(0.205, 0.135)调到伪白光(0.305, 0.266)。

A series of Eu3+/Tb3+/Tm3+ single/co-doped NaLa(MoO4)2 (NLM) phosphors have been synthesized by microemulsion-hydrothermal method. Phosphor crystal structure, morphology and luminescent properties were tested and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy. The results show that the prepared samples are all tetragonal single crystals. By way of substitution, the sites of La3+ are replaced by Eu3+, Tb3+and Tm3+. Morphology of the samples are tetragonal sheet structure and the size of particles is 1~1.5 μm. When the doping concentration of Eu3+ is 9%, NLM∶9%Eu3+ phosphor emission peak is the strongest at 616 nm, the critical transfer distance (Rc) between Eu3+ in the NLM matrix is about 15.20  at this time. At the emission spectrum of NLM∶9%Eu3+, the peak at 591 nm is the magnetic dipole transition of 5D0 to 7F1 of Eu3+. The peak at 616 nm is the electric dipole transition of 5D0 to 7F2 of Eu3+. Electric dipole transition emission intensity is about 10 times of the strength of the magnetic dipole transition. This indicates that Eu3+ is located at noninversion symmetry site. By Fixing Eu3+ (Tb3+) concentration and varying the concentration of Tb3+ (Eu3+), the energy transfer mechanism between Eu3+ and Tb3+ was studied. By adjusting the Eu3+, Tb3+and Tm3+ doping concentrations, tunable luminescence of visible light region is implemented under the single matrix. The luminescence of NLM∶x%Eu3+, y%Tb3+, z%Tm3+ phosphors are translated from blue (0.205, 0.135) to pseudo-white (0.305, 0.266) under 360 nm irradiation.