We report large photoluminescence (PL) enhancement of green-emitting Ba2SiO4:Eu2+ phosphors prepared in an eutectic Li2CO3 melt as a flux. Among the phosphor materials synthesized using low-purity precursors (99%-pure BaCO3 and 99.6%-pure SiO2), the emission intensity of Ba2SiO4:(Li0.02,Eu0.02) (Li = 200% excess) is found to be 470% as high as that of Ba2SiO4:Eu0.02 (no-Li) and in fact is almost equivalent to that of Li-undoped Ba2SiO4:Eu2+ synthesized using ultrapure precursors (99.98%-pure BaCO3 and 99.995%-pure SiO2). In combination with the results from PL measurements and inductively coupled plasma mass spectrometry (ICP-MS), the elemental distribution of the products and melts found from time-of-flight secondary ion mass spectrometry (TOF-SIMS) directly indicates that the excess Li2CO3 autonomously removes the impurities that were originally contained in the low-purity precursors, in particular SiO2, and thus critically improves the photoluminescence efficiency of the material. The newly found Li flux effect on large PL enhancement may not only contribute to more economic production of phosphors but provide a platform for discovery of new efficient phosphors for solid state lighting.
ASJC Scopus subject areas
- Chemical Engineering(all)