Unusual intrinsic luminescence of the host and energy transfer process in YVO4:Er phosphors

YVO₄:Er³⁺ phosphors were prepared by solid state reaction method. The X-ray diffraction results testify the pure tetragonal YVO₄ crystalline phase. The emission spectra of the samples show the obvious intrinsic luminescence of the hosts even though the concentration of the dopants has reached nominal 6 mol%, which is unusual since it is believed that the energy transferring from VO₄³⁻ to rare-earth ions occurs efficiently, thus the intrinsic luminescence of the host disappears when the concentration of the dopants is higher than ∼1 mol%. The comparison of the photoluminescence excited at 320 nm (the absorption of vanadate host) and 380, 490, 525 or 532 nm (the absorption of erbium ions) in visible and infrared range has revealed that energy transfer process has occurred in the system. The study of decay times has revealed that the energy transfer efficiency of the doped YVO₄:Er samples is very low. The low efficiency might be one important reason for the unusual intrinsic emission of the host.