An intense single-component warm-white-light Sr₃Lu(PO₄)₃:Dy³⁺ phosphor for white UV-LEDs

A novel single-phase white-light-emitting phosphor Sr₃Lu(PO₄)₃:Dy³⁺ was prepared by conventional solid-state reaction, and the phases and luminescent properties were well characterized. The excitation spectrum shows that Sr₃Lu(PO₄)₃:Dy³⁺ system can be efficiently excited at wavelength ranging from 350 to 410 nm, which is well-matched with ultraviolet (UV) light-emitting diode chips. Under the UV excitation of 350 nm, the phosphor exhibits intense warm white luminescence with dominating emissions at 482 and 575 nm, corresponding to ⁴F_9/2–⁶H_15/2, ⁴F_9/2–⁶H_13/2 transitions, respectively. With increasing Dy³⁺ concentration in Sr₃Lu(PO₄)₃:Dy³⁺, the CIE coordinates of phosphors change a little in the warm white region and the lifetime decreases from 0.747 to 0.404 ms. Concentration quenching occurs when the Dy³⁺ concentration is beyond 0.08. The critical transfer distance was calculated to be about 18.3 Å and the concentration quenching mechanism was demonstrated to be the electric dipole–dipole interaction according to Dexter’s theory. The temperature dependence of photoluminescence properties were investigated from 25 to 200 °C and the as-prepared Sr₃Lu(PO₄)₃:Dy³⁺ phosphor showed good thermal quenching properties.