Role of Fluxes in Optimizing the Optical Properties of Sr0.95Si2O2N2:0.05Eu2+ Green-Emitting Phosphor

Chlorides of NH 4Cl and SrCl 2 and fluorides of AlF 3 and SrF 2 were added to raw materials acting as the flux for preparing the SrSi 2O 2N 2:Eu 2+ phosphor. The effects of the fluxes on the phase formation, particle morphology, particle size, and photoluminescence properties were investigated. The results revealed that particle size, particle morphology and photoluminescence intensity were largely dominated by the type of the flux material and its adding amount. The chloride-based flux was found to favor the formation of the SrSi 2O 2N 2:Eu 2+ phase. Among the chloride-based fluxes, the sample added with the SrCl 2 flux presented the narrow particle distribution and cleaner surface, with enhanced emission intensity and an increased external quantum efficiency by 68% and 22%, respectively, compared with those of the sample without any flux adding.