Preparation of Ba1.3Ca0.7SiO4:Eu2+,Mn2+ powders using a sol-gel-combustion process and their multiple-photoluminescence

Ba1.3Ca0.7SiO4:0.1Eu2+,xMn2+ (x = 0-0.06) powders were synthesized by a sol-gel-combustion process. The photoluminescence spectra exhibited two distinct A- and B-bands in the green and red regions, respectively. The former was assigned to the 4f7-4f65d transition of the Eu2+ ions, while the latter originated from the Mn2+ ions via energy transfer from Eu2+ to Mn2+. With increasing x value, the intensity of the green A-band gradually decreased, whereas that of the red B-band increased, resulting in a shift of Commission Internationale de l'Eclairage chromaticity coordinates toward lower color temperature regions (warm-white-light emission). The effects of particle morphology, Mn content, and firing temperature on the luminescence properties were observed and discussed. In addition, the efficiency and critical distance of the energy transfer from Eu2+ to Mn2+, quantum efficiencies, and thermal quenching were estimated. The measured results were compared with those of powders prepared by a solid-state reaction process.