Powder Synthesis of Y-α-SiAlON and Its Potential as a Phosphor Host

The Y-alpha-SiAlON fine powders have been successfully synthesized from the system Y2O3-Al2O3-SiO2, by using the gas-reduction-nitridation method. Completion of the nitridation was achieved at temperatures <1500 degrees C without unfavorable carbon contamination and SiC formation. While the presence of Y-containing intermediate phases inhibited the formation of pure alpha' phase in the as-synthesized state, transient liquid-phase formation promoted under the postsynthesis heat treatment enabled the preparation of near single-phase Y-alpha-SiAlON powders. The synthesized Y-alpha-SiAlON:Eu2+ powder exhibited a bright orange emission under near-UV to blue light excitation showing the applicability to the phosphor-converted white light-emitting diodes, whereas the quantum efficiency and the thermal stability were found to be low compared to the Ca-stabilized analogue. The first-principle calculations on the electronic structures of Y- and Ca-alpha-SiAlON Eu2+ were performed for file first time, which clearly demonstrated the effects of modifying cations on their photoluminescent properties.