Luminescent properties and energy transfer mechanism of CaWO4：Sm3+ phosphors

The scheelite-structured CaWO4 phosphors doped with different concentrations of Sm3+ were prepared by precipitation method. Photoluminescence properties of Sm3+-doped CaWO4 samples were studied. Results indicate that red light emission of Sm3+ with higher color purity in the samples can be excited by 404 nm blue light. There are 4f-4f intrinsic emission of Sm3+ and a strong self-excitation emission of CaWO4 when excited by 240 nm short-wave ultraviolet, and the white light emission can be obtained. Experiments show that the best Sm3+ doping concentration is 2%. The energy transfer type between Sm3+ ions was determined to be the electric dipole-electric dipole interaction and the critical energy transfer distance (Dc) was calculated to be 2.0 nm.