MAGNETIC DISACCOMMODATION IN NORMAL SPINEL STRUCTURES

Magnetic disaccommodation is investigated for ferrous ferrites with normal spinel structure. This study shows the presence of a new relaxation process in the temperature region IV (congruent-to 285 K) that has not been detected in inverse spinels. A numerical analysis of the isochronal spectra reveals that it is composed of two simple Debye processes with activation energies close to 0.75 eV and 0.80 eV, and preexponential factors 3 x 10(-13) s. This relaxation is attributed to the formation of an induced anisotropy due to jumps of B-Fe ions into vacancies (as process III), but in presence of a divalent cation occupying an A-site.