A third route to synthesis of green phosphor SrSi2O2N2: Eu2+ from SrO

Abstract The green-emitting phosphor SrSi2O2N2: Eu2+, along with the cyan-emitting phosphor BaSi2O2N2: Eu2+, is a key component for phosphors used to package natural sunlight full-spectrum LED devices. Thereby, the synthesis of high-efficiency and thermal-stability luminous SrSi2O2N2: Eu2+ with an economic approach is very important for the development of LED industry. In this work, the syntheses of SrSi2O2N2: Eu2+ phosphors were optimized from four aspects: strontium sources, reaction atmospheres, reaction vessels, and reaction fluxes. Meanwhile, the relationship among photoluminescence performances, crystal structures, and morphologies were examined. The results show that the synthesis of SrSi2O2N2: Eu2+ from SrO and Sr(NO3)2 sources are beneficial to obtain N-rich oxynitide structure, which is helpful to improve luminescence. By employing SrCO3 and Sr(NO3)2 as strontium sources, however, the SrSi2O2N2: Eu2+ is O-rich and the by-product Sr2Si5N8:Eu is introduced. The optimal conditions for the synthesis of SrSi2O2N2: Eu2+ is by utilizing SrO as a strontium source, in N2 atmosphere, adopting Mo crucible, and adding NH4Cl as flux. The quantum yield of the optimal SrSi2O2N2: Eu2+ phosphor under the excitation of 380 nm reaches up to 100%.