Eu3+掺杂CaMoO4微米荧光粉发光性质的研究

运用化学沉淀的方法合成了不同Eu³⁺掺杂浓度CaMoO₄微米荧光粉样品, 详细研究了样品的光致发光性质. 研究表明: CaMoO₄: Eu可以被蓝光或近紫外光有效激发, 实现高色纯度的红光发射; 样品的黄昆因子数值数量级为10^-2, 是一种弱电声耦合材料; 样品中Eu³⁺的跃迁强度参数(Ω₂)随着掺杂浓度的提高而增大, 但量子效率却随着掺杂浓度的提高而减小; 通过对样品发光的浓度猝灭曲线的分析, 确定Eu³⁺的理想掺杂浓度为25%, 并判断出Eu³⁺在CaMoO₄基质中通过交换相互作用实现能量传递. 沉淀法制备的CaMoO₄: Eu微米荧光粉具有发光色纯度好, 制备工艺简单, 耗时较少的优点, 是一种性能优异的红色荧光粉材料.

Luminescence properties of Eu3+ doped CaMoO4 micron phosphors

Eu³⁺ doped CaMoO₄ micron phosphors of different concentrations were prepared by chemical precipitation method. The photoluminescence properties were studied in detail. The X-ray diffraction measurements indicate that the samples are scheelite structure, and doping Eu³⁺ enlarge the lattice parameter of host material. The scanning electron microscope images show that the particle morphology is near-spherical and the size is 4-5 μm. The excitation and emission spectra of CaMoO₄:Eu show that CaMoO₄:Eu can be effectively excited by blue light and near UV-light, and the red light emission of high colour purity can be realized. The electron-phonon coupling properties were also studied. The results indicate that the magnitude of Huang-Rhys factor is 10^-2, so the CaMoO₄:Eu is a weak electron-phonon coupling material. The results also indicate that the Huang-Rhys factor increases with the increase of concentration. It is probably because that increasing the doping concentration enhances the lattice relaxation. The transition intensity parameter Ω₂ of Eu³⁺ enlarges while the concentration is increasing. Because Ω₂ and the luminescent center environment are closely related, the numerical value of Ω₂ enlarges with the increase of degree of environmental disorder. But Ω₄ doesn't have obvious change. It can be explained that the environmental sensitivity level of Eu³⁺⁵D₀→⁷F₂ transition is higher than that of ⁵D₀→⁷F₄ transition. The quantum efficiency of Eu^{3+ 5}D₀ energy level decreases with the increase of doping concentration. This can be attributed that the enhancement of Eu³⁺ doping concentration enlarges the energy transfer rate between luminescent centers, so the energy of excited electrons can be transferred to quenching center more easily and then the nonradiative relaxation rate of excited electrons increases. The best doping concentration of Eu³⁺ is 25% by drawing the concentration quenching curve. Furthermore, the energy transfer type of Eu³⁺ in CaMoO₄ host is confirmed to be exchange interaction and the critical distance is calculated to be 8.4 Å. The chromaticity coordinate of CaMoO₄:Eu phosphors is (0.654, 0.334), so the samples have high colour purity. The study indicates that CaMoO₄:Eu micron phosphor prepared by chemical precipitation method is a red phosphor material with excellent property.