Synthesis, crystal structure and photoluminescent properties of Eu3+ ion-activated R4MoO9 (R = Y, Gd, and Lu)

Rare earth molybdates R4MoO9 (R = Y, Gd, and Lu) with Eu3+ ion-doped were synthesized by solid-state reaction. The phase structure, optical absorption and photoluminescence properties of the as-prepared powder samples were studied. The powder X-ray diffraction patterns indicated that all the compounds crystallized in a hexagonal structure, and the lattice parameters reduced in the order of the ionic radii of R. The UV–visible diffuse reflectance spectra revealed that the compounds had a strong absorption of near-UV light due to the excitation of MoO6 groups in the host lattices. The energy absorbed by the host lattices could then be transferred to doped Eu3+ ions, resulting in red emission due to the f–f transitions of Eu3+ ions. The optical absorption and photoluminescence properties of the compounds indicated that they might be candidates as the color-conversion red phosphors for solid-state lighting.