关键词: 白光LED, 钼酸盐, 共沉淀法, 稀土发光, 能量传递

Abstract: Pb²⁺ doped CaMoO₄∶Dy³⁺,Eu³⁺ phosphors were synthesized by coprecipitation method. The phase composition, luminescence characteristics and energy transfer efficiency between activated ions were characterized and analyzed by X-ray diffractometer and fluorescence spectrophotometer. The results show that the CaMoO₄∶Dy³⁺,Eu³⁺doped with Pb²⁺ phosphor samples have no new diffraction peaks compared with the undoped phosphor samples. The above shows that Pb²⁺ is a good substitute for Ca²⁺ enters into the crystal lattice. The unit cell parameters are a=b=0.548 9 nm, c=1.275 3 nm, Z=2 belongs to the tetragonal crystal system for CaMoO₄∶0.05Dy³⁺,0.15Eu³⁺,0.15Pb²⁺ phosphor. Under the excitation of 391 nm wavelength, it can be seen that 484 nm blue light emission peak attributes to Dy³⁺(⁴F_9/2→⁶H_15/2), 575 nm is the yellow light emission peak produced by Dy³⁺ (⁴F_9/2→⁶H_13/2) transition, 593 nm is the orange light emission peak produced by Eu³⁺ (⁵D₀→⁷F₁) transition, and 619 nm is the red light emission peak produced by Eu³⁺ (⁵D₀→⁷F₂) transition. The critical transfer distance between Dy³⁺ and Eu³⁺ in CaMoO₄∶Dy³⁺,Eu³⁺ phosphors can be obtained by calculation, which is 1.542 6 nm. The energy transfer mechanism is dipole-quadrupole interaction, the energy transfer efficiency is close to 60.31%, and the maximum sample energy transfer efficiency increases to 72.40% for Pb²⁺ doped phosphor. Therefore, it is concluded that doping with Pb²⁺ can greatly increase the energy transfer efficiency between Dy³⁺ and Eu³⁺ and improve the luminous performance of phosphors, so it has important research significance in the field of white LEDs.

Key words: white LED, molybdate, coprecipitation method, rare earth luminescence, energy transfer