Magnetism of nanostructured iron nitride (Fe–N) systems

Abstract

The recent experimental research on magnetism of nanostructured iron nitride (Fe-N) systems like ϵ-Fe3N, ϵ-Fe3–xNixN, ϵ-Fe3–xCoxN (x = 0.1 to 0.8), γ′–Fe4N and γ′–Fe4–xNixN (0.2 ≤ x ≤ 0.8) are reviewed. In nanoscale dimension, intrinsic magnetic properties (σs, Tc, Hic, Hif) of nanocrystalline particles of pure and substituted γ′–Fe4N and ϵ-Fe3N nitrides are found to change due to spin pairing effects, lattice expansion due to interstitial nitrogen, inter-sublattice interactions, random exchange anisotropy, superparamagnetic relaxation and randomly canted spin structures at the surface. The magnetic interactions among the nanoparticles affect the superparamagnetic relaxation and exhibit spin-glass like ordering in ZFC/FC measurements. Mossbauer studies corroborate to the observed magnetic properties. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)