J. Phys. IV France 07 (1997) C1-525-C1-526
Cationic Distribution in Defect Co-Mn Ferrites from Neutron DiffractionE. Elbadraoui1, J.L. Baudour1, F. Bouree2, Ph. Tailhades3 and A. Rousset3
1 Laboratoire Matériaux Multiphasés et Interfaces, E.A. 1357, Université de Toulon, BP. 132, 83957 La Garde cedex, France
2 Laboratoire Léon Brillouin, CEN Saclay, 91191 Gif sur Yvette cedex, France
3 LCMI, URA 1311 du CNRS, UPS, 118 route de Narbonne, 31062 Toulouse cedex, France
Submicron stoichiometric cobalt manganese ferrites oxidized in air, at low temperature (<500°C) give defect spinel ferrites which exhibit a substantial increase in coercivity, reaching a maximum for ferrites oxidized near 350°C and slowly cooled (5°C/min) from the oxidation temperature. Two [MATH] samples oxidized at 350°C but exhibiting notably different coercivities because of different cooling rates (Hc=1750 Oe after quenching ; Hc=2350 Oe after slow cooling) have been analyzed by neutron diffraction at T=6K. They exhibit almost exactly the same structural and magnetic parameters, indicating that the difference between the coercivities has a purely local origin. Similar cationic distributions have been inferred. Neutron diffraction reveals a classical collinear ferrimagnetism on the A and B sublattices of the spinel structure.
© EDP Sciences 1997