The effect of Ta on structure and magnetic properties in Fe–N films

Microstructure and magnetic properties of Fe–Ta–N alloy films near the eutatic composition were studied. The four systematic alloy films with different Ta content were prepared by reactive sputtering. The dependence of structures and magnetic properties on Ta and annealing were investigated by VSM and X-ray diffraction. It is found that Ta atoms replace Fe in α-Fe lattice and have strong affinity for nitrogen, which inhibits the formation of γ-Fe4N phase in Fe–Ta–N films. The TaN phase precipitates in grain boundaries and suppresses the growth of α-Fe(N) crystalline during annealing. Coercivity varies with the change of microstructure.