Structure, luminescence properties and energy transfer of Dy3+ and Eu3+ codoped KBa(VO4) phosphor

Novel single-phased white-light-emitting and color tunable KBa(VO4):Dy3+, Eu3+ phosphors were synthesized by solid-state reaction method. The crystal structures, luminescence properties, lifetime, and energy transfer mechanism were investigated in detail. A series of characteristic emissions of Dy3+ and Eu3+ were observed in the emission spectra at around 486 nm, 578 nm, 663 nm and 617 nm when excited at 349 nm. With the increase of Eu3+ concentration, the emission intensity and the decay lifetime of Dy3+ decreased, which proved the existence of the energy transfer from Dy3+ to Eu3+ in the KBa(VO4) host. It was found that energy was transferred from F-4(9/2) level of Dy3+ to the Do level of Eu3+ by dipole-dipole interaction and the critical distance between Dy3+ and Eu3+ was 12.82 angstrom. In the case of Dy3+ and Eu3+ codoped phosphors, the color coordinates are very sensitive to the incorporation of Eu3+ ions and the correlated color temperature is improved with the introduction of Eu3+ ions. With 10 mol% Eu3+ phosphor can obtained maximum energy transfer efficiency of 83%. The experimental research shows that KBa(VO4): xDy(3+), yEu(3+) phosphors are promising materials for white UV LEDs.