Some Properties of Quenched Magnesium Ferrites

A study has been made of the magnetic properties of the system of quenched magnesium ferrites (Mg_x^IIFe_1−x^III) · (Mg_1−x^IIFe_1+x^III)O₄, where x, the fraction of magnesium ions in tetrahedral sites, varies from 0.14 to 0.26. Included among the properties examined are: saturation moment, Curie point, initial permeability, and coercive force. A limited study of the kinetics of the cation redistribution has also been made. Samples quenched from 1100°C and then tempered at 600°C require somewhat less than 16 hours to attain an equilibrium cation distribution at the latter temperature. The approach to equilibrium is consistent with a model in which the rate of approach is proportional to $\exp {\mathrm{(-\theta }}_0{\mathrm{\prime +\theta }}_1\mathrm{\prime x)/T}$ where θ₀′ and θ₁′ are activation constants.