Influence of Bi2O3 flux in the structural and photoluminescence properties of SrAl2O4:Eu2+ phosphors

SrAl2O4:Eu2+ phosphors with various content of Bi2O3 flux were synthesized and analyzed. It was observed that the crystallinity and the particle size of the phosphors were increased with the addition of Bi2O3 flux. These phenomena are considered to be caused via the melting of the Bi2O3 flux particles during the synthesis of the phosphors. The melted Bi2O3 flux increased the mobility and homogeneity of solid reactants, thereby enhancing the photoluminescence intensity of the phosphors. SrAl2O4:Eu2+ phosphors with Bi2O3 as the flux exhibited a broad green emission with a peak at 520 nm. The highest photoluminescence emission intensity was observed when 5 mol% Bi2O3 flux was added into the phosphors. The emission is due to 4f65d→4f7 (8S7/2) transitions of the Eu2+ ions. Moreover, Bi2O3 flux extended the application of the ultraviolet excited phosphors toward the blue-light excited phosphors. Nevertheless, the influence of Bi2O3 on the afterglow and the emission color of SrAl2O4:Eu2+ phosphors were not significant. This research indicated that Bi2O3 flux is effective flux for synthesizing SrAl2O4:Eu2+ phosphors.