[en] The structural and magnetic properties of the granular iron nitride-alumina composite materials: (FexN)(0.2)(Al2O3)(0.8) and (FexN)(0.6)(Al2O3)(0.4), fabricated using high-energy ball milling have been determined by using X-ray diffraction, Mossbauer spectroscopy, and magnetization measurements. The Mossbauer spectra, fit with a distribution of hyperfine fields between zero and 40 T. indicate that the weighted average field decreases with increasing milling time. The isomer shift increases with milling time because of a reduced iron 4s-electron density at the grain boundaries. Coercive fields as high as 325 and 110 Oe are obtained for (FexN)(0.2)(Al2O3)(0.8) at 5 and 300 K, respectively; the increase in the coercive field upon cooling indicates the presence of superparamagnetic particles. The coercive field increases with milling time because of the reduced particle size. The decrease in the magnetization results from the increase in both the superparamagnetic fraction and the concentration of surface defects with increased milling time.
Disciplines :
Physics
Author, co-author :
Mishra, S. R.
Long, G. J.
Grandjean, Fernande ; Université de Liège - ULiège > Département de physique > Département de physique
Hermann, Raphaël ; Université de Liège - ULiège > Département de physique > Département de physique
Roy, S.
Ali, N.
Viano, A.
Language :
English
Title :
Magnetic properties of iron nitride-alumina nanocomposite materials prepared by high-energy ball milling
Publication date :
2003
Audience :
International
Journal title :
European Physical Journal D -- Atoms, Molecules, Clusters and Optical Physics
ISSN :
1434-6060
Publisher :
Springer Science & Business Media B.V., New York, United States - New York