Magnetic properties of α′-FeNx and α"-Fe16N2 nitrides

In the present work we studied the magnetic properties of alpha'-FeNx and alpha"-Fe16N2 nitrides. Powder samples of nitrides were prepared by nitriding of iron powder in the mixture of H-2 and NH3. The desired alpha"-Fe16N2 was prepared by the conventional method-tempering of samples containing alpha'-FeNx. The maximum content of alpha"-Fe16N2 in the resulting mixture with alpha-Fe and gamma-FeNx was up to 60 wt %. The presence of individual pha;es was determined by XRD analysis and Mossbauer spectroscopy. The specific magnetic moment of samples was measured in SQUID magnetometer and that of individual phases was evaluated using data of the phase composition. Along with magnetic measurements the average magnetic moments of the present Fe atoms were evaluated from hyperfine fields derived from Mossbauer spectra. The average specific magnetization of alpha"-Fe16N2 determined by XRD, Mijssbauer phase analysis together with SQUID measurements and from hyperfine fields of Mossbauer spectra were 246, 244 and 240 emu g(-1), respectively. (C) 1998 Elsevier Science S.A.