Role of Fluxes in the Synthesis and Luminescence Properties of Ba3Si6O12N2:Eu2+ Oxynitride Phosphors by Microwave Sintering

Eu2+ activated Ba3Si6O12N2 oxynitride green phosphors were synthesized by microwave sintering method with the aid of fluxes, namely BaCl2, H3BO3, KF, and NH4F. We employed a combination of X-ray diffraction, photoluminescence spectra and scanning electron microscopy measurements, in conjunction with detailed quantum efficiency (QE), life time and thermal quenching studies of luminescence properties to understand the origins of the improved luminescence properties. The results showed that the photoluminescence intensity of the phosphors was increased obviously by using varied fluxes and the intensity rise was recorded in order of fluxes as following: H3BO3 > KF > BaCl2 > no flux > NH4F. The maximum emission intensity of the Ba3Si6O12N2: Eu2+ phosphor was achieved at containing 1.0wt% H3BO3, due to the high crystallinity, narrow particle-size distribution and smooth surface, which showed low thermal quenching, shorter life time and increased external quantum efficiency, compared with that of the sample with other fluxes or without flux.