Abstract
Detailed measurements on the variation of magnetization with applied field and temperature in the region of the Curie point are reported for nickel ferrite, cobalt ferrite, several cobalt-zinc and nickel-zinc ferrites, for manganese ferrite and for a magnesium-zinc ferrite. New observations on the magnetocaloric effect in magnesium zinc ferrite have also been made. Anomalies observed in the form of the curves of constant magnetization of ferrites with mixed structure but not with the fully inverse structure are tentatively ascribed to the presence in the specimens of two kinds of region with different Curie points. X-ray examination of some of the ferrites showed that it is unlikely that major variations of composition are responsible for the anomalies.