Preparation and Photoluminescence Properties of Pr3+ Ion-Doped Ca2LaTaO6 Phosphors

In this study, Pr3+ ion-doped Ca2LaTaO6 phosphors were synthesized using a vibrating milled solid-state reaction with metal oxides and calcined in air at 1100°C for 8 h. The crystal structure and photoluminescence properties were also investigated. The x-ray powder diffraction patterns show that all of the peaks can be attributed to monoclinic Ca2LaTaO6 phase with increasing Pr3+ ion doping. The scanning electron microscopy images show that the particles are irregular, with the most uniform distribution being obtained for Pr3+ ion concentration of 3 mol.%. The emission spectra of Ca2(La1−xPrx)TaO6 phosphors showed a dominant green emission peak at 490 nm under excitation at 451 nm, which was due to the 3P0 → 3H4 transition. A series of weak emission peaks at 531 nm, 544 nm, 615 nm, 621 nm, and 652 nm were assigned to the 3P0 → 3H5, 1D2 → 3H4, 3P0 → 3H6, and 3P0 → 3F2 transitions of Pr3+ ions, respectively. In addition, the emission intensities of the Ca2(La1−x Prx)TaO6 phosphors increased then decreased as the Pr3+ ion concentration was increased, and the maximum emission intensity occurred for x of 0.03, corresponding to an average grain size of 41.5 nm with critical distance of 16.32 Å. The Commission Internationale de l’Eclairage color chromaticity coordinates for the Ca2LaTaO6:Pr3+ phosphors were all located in the green region, but shifted from (x = 0.145, y = 0.463) to (x = 0.119, y = 0.471) as the Pr3+ ion concentration was increased from 0.5 mol.% to 10 mol.%.