Magnetic composites composed of iron-nitride nanograins dispersed in a silver matrix

Magnetic nanocomposites in which iron nitride nanograins are dispersed in a silver matrix were synthesized by nitriding iron-oxide nanograins buried i n the matrix. The iron nitride nanocomposite is regarded as a promising mat erial from viewpoint of magnetic applications, since iron nitride family in volves various magnetisms with large magnetic moments comparable to that of metallic iron and chemical stabilities better than those of metallic nanop hase. Ferromagnetic iron nitride of gamma'-Fe4N or epsilon-Fe2-4N was selec tively obtained in the silver matrix by controlling the nitriding potential during the reaction with ammonia gas streams with various flow conditions. The composites were characterized with XRD, TEM and the magnetic propertie s were studied by a SQUID magnetometer. (C) 1999 Acta Metallurgica Inc.