High dispersibility and enhanced luminescence properties of BaMgAl10O17:Eu2+ phosphors derived from molten salt synthesis

A Facile Method Using a Flux to Improve Quantum Efficiency of Submicron Particle Sized Phosphors for Solid-State Lighting Applications

“…The process is a well-known method for crystal growth in materials [1,11,12]. A flux is typically used in preparing phosphor powders through a solid-state reaction method, producing regular-shaped particles and enlarged crystallites, which cause the emission intensity to be enhanced [7][8][9][13][14][15][16][17]. However, this process is rarely researched for nanocrystalline, submicrometer-sized phosphors prepared by wet chemical processes [18][19][20][21].…”

“…However, this process is rarely researched for nanocrystalline, submicrometer-sized phosphors prepared by wet chemical processes [18][19][20][21]. Table 1 shows the effect of various flux compositions on phosphor properties for application in nUV-LED lighting [7][8][9][13][14][15][16][17][18][19][20][21]. In each case, the phosphor properties (e.g., quantum efficiency, particle size and surface smoothness) were enhanced with the addition of a flux.…”

“…In each case, the phosphor properties (e.g., quantum efficiency, particle size and surface smoothness) were enhanced with the addition of a flux. In fact, after adding a flux, aluminates and oxides showed enlarged particles and smooth particle surfaces [7,8,15,18], silicates and oxy-nitrides have larger crystallite sizes and regular particle morphology [14,16,19,20]. Most importantly, these phosphors all have enhanced emission intensity or quantum efficiencies with the addition of a flux.…”

“…A flux is typically mixed with reactants [7,8,[14][15][16]19] or as-synthesized product [20] before an annealing step; thus, is present as the molten phase during the post-synthesis annealing process. Since the flux material should be evaporated after annealing to avoid formation of impurities or second phases in the final product, the melting and boiling temperatures should be considered in relationship to the annealing conditions (temperature, atmosphere), when selecting a flux material.…”

“…A low Φ is a drawback of nanocrystalline-sized phosphors; therefore, the main goal of this study was to improve the Φ using several different types of flux materials. NH 4 F, NH 4 Cl, and H 3 BO 3 were selected as flux materials from the reported flux candidates [7][8][9][13][14][15][16][17][18][19][20] due to their low melting and boiling temperatures ( Table 2), which are expected to decompose or evaporate during annealing process. Additionally, the large (>30%) ionic radii difference between the flux and the phosphor components indicates that flux contamination of the phosphor is unlikely to occur.…”