Characterization of Nd2AlO3N and Sm2AlO3N oxynitrides synthesized by carbothermal reduction and nitridation

The Nd2AlO3N and Sm2AlO3N oxynitrides with the K2NiF4-type structure have been prepared from oxide mixture at 1250 °C using the carbothermal reduction and nitridation route (CRN). Optimization of the process is discussed to prevent surface oxidation of the oxynitrides during the synthesis. The absorption of Nd2AlO3N and Sm2AlO3N, orange and yellow respectively, has been characterized by diffuse reflectance as well as their thermal stability versus oxidation by thermogravimetric analyses.

Research highlights
► Carbothermal reduction and nitridation leads to rare earth aluminum oxynitride starting from oxide mixture.
► Absorption shifts towards visible in Nd2AlO3N (orange) and Sm2AlO3N (yellow).
► Oxynitrides are stable up to 600 °C in air.
► The so-called “intermediate phase” phenomenon is evidenced in Sm2AlO3N.