Tunable photoluminescence properties of Sr(1-y)CayMoO4:Sm3+ phosphors (0 ≤ y < 1)

A series of Sr(1-x-y)CayMoO4:xSm(3+) (0 ≤ x ≤ 7 mol% and 0 ≤ y < 1) phosphors was synthesized by a conventional solid-state reaction method in air, and their structural and spectroscopic properties were investigated. The optimal doping concentration of Sm(3+) in SrMoO4:Sm(3+) phosphor is 5 mol%. Under excitation with 275 nm, in Sr(1-x-y)CayMoO4:xSm(3+) (0 ≤ x ≤ 7 mol% and 0 ≤ y < 1) phosphors, the emission band of the host was found to overlap with the excitation bands peaking at ~ 500 nm of Sm(3+) ion, and the energy transfer from MoO4 (2-) group to Sm(3+) ion can also be observed. The International Commission on Illumination (CIE) chromaticity coordinates of Sr(0.95-y)CayMoO4:0.05Sm(3+) phosphors with excitation 275 nm varied systematically from an orange (0.4961, 0.3761) (y = 0) to a white color (0.33, 0.3442) (y = 0.95) with increasing calcium oxide (CaO) concentration. However, Sr(0.95-y)CayMoO4:0.05Sm(3+) phosphors with excitation at 404 nm only showed red emission and the energy transfer between MoO4(2-) group to Sm(3+) ion was not observed. The complex mechanisms of luminescence and energy transfer are discussed by energy level diagrams of MoO4(2-) group and Sm(3+) ion.