Structure and luminescence properties of CaWO4-EuMO4 (M=Nb, Ta) solid solution

The 0.8CaWO₄-0.2EuMO₄ (M = Nb, Ta) solid solution and Eu³⁺, Ta⁵⁺ and Nb⁵⁺ single doped CaWO₄ were prepared by a high-temperature solid state reaction technique. Experiments show that the addition of Nb⁵⁺ and Ta⁵⁺ can increase the red luminescence of Eu³⁺ in CaWO₄. In this paper, the composition and structure of solid solution were analyzed by X ray diffraction (XRD), Fourier transform infrared spectrum and Raman spectrum analysis. The luminescence properties of the solid solution were studied by means of stable photoluminescent spectra, diffuse reflectance spectra (DRS), fluorescent decay curves and variable temperature spectra. By combining structural analysis, J-O theoretical calculation and experimental results, we believe that the significant improvement of the emission efficiency comes from the decrease of non-radiation relaxation rate.