EFFECTS OF CATION DISTRIBUTION ON SUPEREXCHANGE INTERACTION IN COBALTFERRITES

The effects of the cation distribution change on the superexchange par ameters and magnetic properties of cobalt ferrite powders were investi gated. The cation distribution change of cobalt ferrite powders with q uenching treatment was confirmed from the Mossbauer experiments. The e xchange interaction parameters i.e. J(AA), J(BB) and J(AB), Neel tempe rature of slow-cooled and quenched CoFe2O4 powders were calculated fro m the variation of the magnetization with temperature on the basis of the two-sublattice model. With a quenching treatment of CoFe2O4, the t hermal magnetization was changed, and this was attributed to the catio n distribution change of cobalt ferrites. The absolute values of J(AB) increased with the quenching treatment of CoFe2O4, while those of J(A A) and T-N decreased. The values of J(BB) of cobalt ferrite remained t he same with the quenching treatment. This result suggested that the d ecrease of T-N of CoFe2O4 with quenching may be attributed to the decr ease of J(AA).