Effect of metal halide fluxes on the microstructure and luminescence of Y3Al5O12:Ce3+ phosphors

Yellow-emitting Y2.95Al5O12:0.05Ce (YAG:Ce) phosphor particles with high luminescence efficiency under 450 nm ultraviolet (UV) excitation were prepared by a heat treatment of submicrometer-sized oxide powder mixture in a reducing atmosphere at 1550 °C. Prior to the heat treatment, the oxide mixture was blended with 5 wt% of metal halides – BaF2, BaCl2, NaF, NaCl, and KF – as a flux. It was observed that YAG:Ce particles prepared with fluorine containing flux demonstrated spherical morphology, high photoluminescence properties, and diameters of 5–20 μm, whereas those prepared with chlorine were small-sized particles (≤5 μm) with relatively low intensity. The highest relative photoluminescence (PL) intensity (∼118%) was obtained for the samples prepared with 5% BaF2. A set of rules was established for the formation of spherical YAG:Ce particles in the presence of this flux.

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► We have developed a promising approach that enables the production of micrometer-sized spherical YAG:Ce particles.
► The highest relative photoluminescence (PL) intensity of prepared YAG:Ce was 118%.
► Formation of spherical shape and provision of high emission intensity of YAG:Ce were facilitated by fluoride flux.