ABSTRACT
Inorganic phosphors are composed of a host lattice doped with a small amount of impurity ions that activate luminescence. Most of these materials are oxides, sulfides, fluorides, halides, and oxysulfides doped with transition metal ions or rare-earth ions. The integration of nitrogen (N) in silicates or aluminosilicates produces a wide range of complex structures with increased flexibility compared to the oxosilicates, and thus a new class of materials, nitridosilicates, nitridoaluminosilicates, and sialons, are obtained. The host lattice of these phosphors is based on nitridosilicates, oxonitridosilicates, or oxonitrido-aluminosilicates, which are derived from silicates by formal exchanges of O and Si by N and Al, respectively. The most usual approaches for synthesizing oxynitride phosphors are solid-state reactions and gas-reduction–nitridation. The solid-state reaction involves the reaction among chemical components including metals, nitride, and oxide starting powders at high temperatures (1400–2000°C) under an N2 atmosphere.
