Preparation of Eu-doped β- and 15R-SiAlONs by ammonia nitridation of the precursor obtained using aluminum glycine gel

Synthesis of Eu-doped β- and 15R-SiAlONs was studied by the ammonia nitridation of precursors derived from an α-Si3N4 fine powder dispersed in aluminum glycine gel with various Si/Al ratio and post-annealing in a nitrogen pressure furnace. The largest amount of β-SiAlON was observed in the product at 1750 °C for Si/Al = 1/1 with small amounts of both α- and 15R-SiAlON impurities. The product showed two emissions at around 420 nm and 560 nm. The emission intensities decreased with increasing amount of β-SiAlON. The former and latter emissions were assigned to Eu2+ in the 15R- and α-SiAlONs impurities. A mixture of Eu-doped 15R-SiAlON with α-Al2O3 impurity was obtained for Si/Al = 1/6, using AlN together with Al(NO3)3·9H2O in a 2/1 atomic ratio as the aluminum source. It showed a bluish-white emission at 450 nm under 254 nm radiation.