Formation of iron-nitride/silver nanocomposites by ammonia-flow method andnitride phase identification by X-ray absorption near-edge structure

Magnetic nanocomposites in which iron nitride nanograins were dispersed in a silver matrix were synthesized by nitriding iron oxide nanograins buried in the matrix. The ammonia-flow method, in which the solid phase reacted wi th flowing ammonia, was adopted for this synthesis. Several reactions of me tallic iron with NH3 were carried out under various conditions and the resu ltant nitride phases were observed by X-ray diffraction (XRD). Based on the se results, optimum conditions for the synthesis of the nanocomposite were determined, and a nanocomposite containing only gamma'-Fe4N or epsilon-Fe2- 4N was successfully obtained. Phase identification of iron nitride in the c omposite was performed by X-ray absorption near-edge structure (XANES) meas urement, which was found to be more suitable for the present nanocomposites than XRD.