VUV-UV photoluminescence, site occupancy and thermal stability of blue-emitting K2CaP2O7:Eu2+ UV-LED phosphor

Blue-emitting phosphors K2Ca1-xP2O7:xEu(2+) (x = 0.005; 0.010; 0.015) were prepared by a solid-state reaction. The luminescence properties of the phosphors were systematically investigated. VUV photoluminescence spectra of K2Ca1-xP2O7:xEu(2+) exhibit that three distinct bands peaking at 439, 478 and 535 nm can be attributed to the overlap of Eu(1), Eu(2) and Eu(3) emission bands, which are ascribed to the 4f-5d transition of Eu2+. The critical quenching concentration of Eu2+ in K2CaP2O7 phosphor is about 1 mol%, and the critical transfer distance was determined to be 32.23 A. When the temperature turned up to 150 degrees C, the emission intensity of K2Ca0.99P2O7:0.01Eu(2+) sample was 60% of the initial value at room temperature. The activation energy E-a was calculated to be 0.217 eV, which proved the good thermal stability of the phosphor. All the properties indicated that the K2CaP2O7:Eu2+ is promising blue-emitting phosphor for application in LED-based lighting or display systems.