Effects of excitation wavelength and Y3+ content on luminescent properties of YMO4:Dy3+ (M = V, P) phosphors induced by ultraviolet excitation

Y0.99VO4:0.01Dy3+, Y0.99PO4:0.01Dy3+ and YxVO4:0.01Dy3+ phosphors were synthesized by chemical co-precipitation method. All the samples were characterized by X-ray powder diffraction (XRD) and photoluminescence spectroscopy. XRD results show that the samples only have single tetragonal structure and the crystallinity of Y0.99VO4:0.01Dy3+ phosphor is higher than that of Y0.99PO4:0.01Dy3+ phosphor when the heat treatment process is same. Photoluminescence excitation spectra results show that the Y0.99VO4:0.01Dy3+ and Y0.99PO4:0.01Dy3+ phosphors can be efficiently excited by ultraviolet light from 250 nm to 380 nm, the former have a wide Dy3+–O2− charge transfer band ranging from 260 nm to 350 nm including a peak at 310 nm, the latter have four peaks at 294 nm, 326 nm, 352 nm and 365 nm. Emission spectra of all the samples exhibit a strong blue emission (483 nm) and another strong yellow emission (574 nm). Moreover, the yellow-to-blue emission intensity ratio and color temperature of emission of Dy3+ are strongly related to excitation wavelength in Y0.99PO4:0.01Dy3+ phosphor, but it is almost not in Y0.99VO4:0.01Dy3+ phosphor. For YxVO4:0.01Dy3+ (x = 0.94, 0.97, 0.99, 1.01, 1.03) phosphors, with increasing value of x, the body color of phosphor changes from yellow to white and the strongest peak in excitation spectra shifts a little to shorter wavelength. It is detrimental to luminous intensity when Y3+ content deviate stoichiometric ratio, but the influence of Y3+ on the color temperature of emission of YVO4:Dy3+ phosphor is slight.