Tuning the color emission of Gd(P_xV_1−x)O₄:Sm³⁺ phosphors via changing PO₄³⁻/VO₄³⁻ proportion

A series of color-tunable phosphors of Gd(P_xV_1−x)O₄: y at.% Sm³⁺ (x = 0, 0.3, 0.5, 0.7 and 0.8; y = 1, 2, 3 and 4) were prepared by traditional high-temperature solid method. The phosphors were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy, photoluminescence excitation, photoluminescence (PL) and fluorescence lifetime. XRD results suggest that the phosphors can maintain a tetragonal structure when the doping concentration of PO₄³⁻ is less than 0.7 at.%. Gauss fitting analysis indicates that the excitation band of Gd(P_0.5V_0.5)O₄: 2 at.% Sm³⁺ is mainly composed of charge-transfer (CT) bands of VO₄³⁻ (280 nm) and ligand (O²⁻) to metal (Sm³⁺) CT transition (310 nm). A weak VO₄³⁻ emission band centered at 442 nm was observed, and characteristic emission peaks of Sm³⁺ were also observed locating at about 564 nm, 604 nm and 645 nm, respectively. For Gd(P_xV_1−x)O₄: 2 at.%, the intensity of broad band emission from VO₄³⁻ can be regulated by changing the doping proportions of PO₄³⁻/VO₄³⁻, as PO₄³⁻ may block energy transfer from VO₄³⁻ to Sm³⁺. J–O parameters and spectroscopic parameters were also calculated in detail by fitting absorption spectrum. In consequence, the combination of VO₄³⁻ emission and characteristic Sm³⁺ emission in different matrix of Gd(P_xV_1−x)O₄ caused a series of color changing from orange-red to light-blue. And Gd(P_xV_1−x)O₄: 2 at.% Sm³⁺ can be a good candidate for UV-activated color-tunable phosphor.