Solid-state synthesis, characterization and luminescent properties of Eu{sup 3+}-doped gadolinium tungstate and molybdate phosphors: Gd{sub (2-x)}MO{sub 6}:Eu{sub x}{sup 3+} (M=W, Mo)

Red phosphors gadolinium tungstate and molybdate with the formula Gd{sub (2-x)}MO{sub 6}:Eu{sub x}{sup 3+} (M=Mo, W) were successfully synthesized by the solid-state reaction at 900 and 1300 deg. C for 4 h, respectively. The products were characterized by an X-ray powder diffractometer (XRD), TG-DSC, FT-IR, PL, UV-vis and SEM. Room-temperature photoluminescence indicated that the as-prepared Gd{sub (2-x)}MO{sub 6}:Eu{sub x}{sup 3+} (M=Mo, W) had a strong red emission, which is due to the characteristic transitions of Eu{sup 3+} ({sup 5}D{sub 0}{yields}{sup 7}F{sub J}, J=0, 1, 2, 3, 4) for these phosphors. Meanwhile, the {sup 5}D{sub 0}{yields}{sup 7}F{sub 2} is in the dominant position. The emission quantum efficiency of Eu{sup 3+} in the Gd{sub (2-x)}MO{sub 6}:Eu{sub x}{sup 3+} (M=Mo, W) system has been investigated. The XRD results indicate that both Gd{sub 2}WO{sub 6} and Gd{sub 2}MoO{sub 6} belong to the monoclinic system with space group C2/c [A. Bril, G. Blasse, J. Chem. Phys. 45 (1966) 2350-2356] and I2/a [A. Bril, G. Blasse, J. Chem. Phys. 45 (1966) 2350-2356], respectively. SEM images indicate that the shape of Gd{sub 1.96}WO{sub 6}:Eu{sub 0.04}{sup 3+} is aggregated small particles with a mean diameter of about 300 nm, and the shape of Gd{sub 1.96}MoO{sub 6}:Eu{sub 0.04}{sup 3+} is block-like structures. - Graphical abstract: Excellent red phosphors gadolinium tungstate and molybdate with the formula Gd{sub (2-x)}MO{sub 6}:Eu{sub x}{sup 3+} (M = Mo, W) were synthesized by the conventional solid-state reaction at 900 and 1300deg. C for 4 h, respectively. SEM imagines indicate that the morphology of Gd{sub 1.96}WO{sub 6}:Eu{sup 3+}{sub 0.04} has 3D micro-pore network structures better than the block-like Gd{sub 1.96}MoO{sub 6}:Eu{sup 3+}{sub 0.04}. Their quantum efficiency has been investigated.