Eu^(3+)掺杂CaMoO_4微米荧光粉发光性质的研究

Luminescence properties of Eu^(3+) doped CaMoO_4 micron phosphors

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102,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.

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 /22 of Eu3＋ enlarges while the concentration is increasing. Because Y22 and the luminescent center environment are closely related, the numerical value of Ω2 enlarges with the increase of degree of environmental disorder. But Y24 doesn＇t have obvious change. It can be explained that the environmental sensitivity level of Eu3＋ 5D0o→ 7F2 transition is higher than that of 5Do → 7F4 transition. The quantum efficiency of Eu3＋ 5D0 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 A. The chromaticity coordinate of CaMoOa：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.