Preparation of Y3Al5O12:Ce nanophosphors using salt microemulsion method and their luminescent properties

Nano-yttrium aluminum garnet (YAG) is a promising material for use in white light-emitting diodes and biological fluorescent probe. However, its existing preparation methods often suffer from low synthesis temperature and particle agglomeration. Therefore, preparing YAG nanoparticles with both high crystallinity and high dispersibility is difficult, which severely limits the applications of nano-YAG phosphor. This work presents a salt microemulsion method that can yield YAG nanoparticles of size 4–6 nm that are dispersed at a high temperature (1000 °C). Transmission electron microscope analysis shows that the precursor particles are dispersed and isolated by nano-sized potassium sulfate particles. Because the melting point of potassium sulfate is high (1067 °C), the precursors and the YAG nanoparticles are always dispersed and isolated by the solid potassium sulfate salt during calcination at high temperatures, resulting in the formation of dispersed YAG nanoparticles with good crystallinity. The reflection spectrum of nano-YAG exhibited a redshift compared to that of bulk YAG. When the Ce content is 0.06, the nano-YAG phosphor exhibited the highest internal photoluminescence quantum yield of 51.2%, and the decrease in the particle size did not increase the quenching concentration. The nano-YAG prepared at a high temperature also exhibited improved optical stability: The luminescence intensity of the nano-YAG decreased by only~ 16% after 48 h of irradiation using blue laser. The obtained 4–6-nm-sized Y3Al5O12:Ce nanophosphors are expected to be ideal materials for novel fluorescent probes and preparation of transparent ceramics.