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Abstract: In this study, we used oxides (Y2O3, CeO2 and Al2O3) as the raw materials to fabricate YAG:Ce3+ phosphors by a molten salt synthesis (MSS) method. The formation of YAG phase strongly depends on the alumina source and firing temperature. Microstructure characterization indicates that “dissolution-precipitation” mechanism dominates the formation process of YAG in the alkali chlorides melt. Thus, highly active nano-Al2O3 starting powders promote their solution in the melt and guarantee a solute stoichiometric of YAG phase rather than other Y–Al–O compounds. The as-prepared YAG:Ce3+ phosphors show typical yellow emission peaked at 535nm under excitation of 460nm blue light, suggesting that MSS could be a promising method for the preparation of phosphor powders even though oxide raw materials are used. [Copyright &y& Elsevier]

Abstract: Cerium-doped Ca–α-SiAlON phosphors with Ca n−1.5x Si12−m−n Al m+n O n N16−n :Ce x (m=2n, 0.8≤m≤2.4, and 0.02≤x≤0.40) nominal compositions have been synthesized by gas pressure sintering (GPS). The photoluminescence (PL) properties were studied in relation to phase composition, particle morphology, and microstructure. Continuous addition of Ce rare-earth (RE) could enhance the emission intensity of phosphors, which was partially attributed to the formation of increased amount of planar defects where dense doping of Ce ions is achieved. Such enhancement could hold up to x=0.32, above which the emission intensity fell slightly due to the formation of more secondary phases and a surface glassy phase rather than concentration quenching. Finally, possible ways to improve the luminescence properties of Ce-doped α-SiAlON phosphors were discussed through tailoring the composition and microstructure. [Copyright &y& Elsevier]

Abstract: Ce3+-doped β-SiAlON blue phosphors with composition of Ce x Si6−z Al z O z N8−z (0.2≤z≤4) at a fixed x=0.01 were synthesized by the gas pressure sintering method. The phases and photoluminescence properties were found to be directly correlated to the z value. Higher z value would result in the formation of AlN polytypoid impurity phases. The optimal z value resides in the range 0.3≤z≤0.5, by which high purity of β-SiAlON phase, good crystallinity and fine grain size were obtained, leading to the best luminescence properties. These phosphors could be a good candidate for application in white light-emitting diodes using InGaN-based near–ultraviolet chips. [Copyright &y& Elsevier]