Influence of doping alkali metal ions on the structure and luminescent properties of microwave synthesized CaMoO4:Dy3+ phosphors

A series of Ca0.98-xMoO4:Dy-0.02(3+), M-x(+) (M = Li, Na, K, 0 <= x <= 0.16) phosphors were synthesized rapidly using microwave radiation method in 30 min. The effects of doping alkali metal ions on the phase structure and luminescent properties of the phosphors were analyzed using X-ray powder diffraction, scanning electron microscopy, fourier transform infra-red spectroscopy, and fluorescence spectrophotometry. The results confirmed that all the samples were pure tetragonal CaMoO4 structure. The samples consisted of many cubic particles and some irregular polyhedron particles, assembled by fine spherical-like grains. The main emission peak was located at 574 nm, which was attributed to the F-4(9/2) -> H-6(13/2) transition of Dy3+. The addition of alkali metal ions could effectively improve the intensity of the main emission peak. K+ had better improvement on emission intensity than Na+ and Li+. For the series of Ca0.98-xMoO4:Dy-0.02(3+), K-x(+) phosphors, the optimum doping content of K+ was 0.10 with 2.6 times of the emission intensity at 574 nm of the undoped-K+ sample. The color coordinates gradually shifted from yellow-green region to the yellow region with the increasing of K+ content (0 <= x <= 0.10). When x = 0.10, the sample shows the strongest yellow-emitting. (C) 2016 Elsevier B.V. All rights reserved.