Gas-Reduction—Nitridation Synthesis of Nitride Phosphors for Solid-State Lighting

In the last decade, SiAlONs and nitridosilicates have been developed as an important class of phosphor host materials because of their great potentials for solid-state lighting (SSL). However, their low manufacturability (reaction sintering and postsynthesis grinding) is a major obstacle to the widespread use in SSL applications, triggering the intense investigations for developing more sophisticated processing techniques.

In this regard, we have developed the gas-reduction—nitridation (GRN) method, which enables the direct synthesis of nitride fine powders from the multicomponent oxide systems by using an NH₃—CH₄ gas mixture as a reduction—nitridation agent. The GRN-derived powders possess high phase purity, nonaggregated fine particle morphology, and very low impurity absorption throughout emissive regions, all of which meet the demands for phosphor applications. In this talk, our successful applications of the GRN process to the Eu²⁺-activated α-SiAlON and CASN, as well as Ce³⁺-activated La—Si—N phosphors for SSL will be demonstrated.