Color Tunable Single-Phase Eu2+ and Ce3+ Co-Activated Sr2LiAlO4 Phosphors

High purity Eu2+ and Ce3+ singly and co-activated Sr2LiAlO4 phosphors were successfully synthesized through a facile combustion reaction. Fabrication of color tunable, single-phase phosphors was achieved by varying the Eu2+ /Ce3+ ratio that utilized the energy transfer between Ce3+ to Eu2+. For the singly activated compositions, the highest quantum efficiencies were 25\% and 40\% for Sr1.998Eu0.002LiAlO4 and Sr1.998Ce0.002LiAlO4 respectively. The emission of Sr2LiAlO4:Ce3+ and the excitation of Sr2LiAlO4:Eu2+ overlap in the range of 400 nm - 500 nm so that energy transfer from Ce3+ {$\rightarrow$} Eu2+ takes place. The emission color of Eu2+ and Ce3+ co-activated Sr2LiAlO4 changes from blue, to cool-white, to green depending on the activators concentrations. The maximum quantum efficiency of Eu2+ and Ce3+ co-activated Sr2LiAlO4 was 55\% when the concentrations of Eu2+ and Ce3+ were 0.005 and 0.001, respectively, which demonstrates that the corresponding quantum efficiency improves by co-activating with Eu2+ and Ce3+.