Ferrite with constricted magnetic hysteresis loop

Claim 1

A PROCESS FOR PREPARING COBALT-MODIFIED FERRITES SELECTED FROM THE CLASS CONSISTING OF MAGNESIUM-ZINC-IRON FERRITES AND MAGNESIUM-CADMIUM-IRON FERRITE, SAID FERRITES CONTAINING 0.1 TO 5% BY WEIGHT OF COBALT OXIDE AND OVER 50 MOL PERCENT OF IRON OXIDE, THE WEIGHT PROPORTION OF MAGNESIUM, ZINC AND IRON OXIDES IN SAID MAGNESIUM-ZINC IRON FERRITE BEING WITHIN THE AREA A-B-C-D OF FIG. 3 OF THE DRAWING AND THE WEIGHT PROPORTION OF MAGNESIUM, CADMIUM AND IRON OXIDES OF THE MAGNESIUM CADMIUM IRON FERRITE BEING WITHIN THE AREA A-B-C-D OF FIG. 4 OF THE DRAWING, COMPRISING PREPARING A POWDERED COMPOSITION CONSISTING ESSENTIALLY OF FERRIC OXIDE, MAGNESIUM OXIDE, COBALT OXIDE AND AN OXIDE SELECTED FROM THE GROUP CONSISTING OF ZINC OXIDE AND CADMIUM OXIDE IN THE PROPORTIONS REQUIRED TO PROVIDE AT LEAST 50 MOL PERCENT OF FERRIC OXIDE AND 0.1 TO 5% BY WEIGHT OF COBALT OXIDE, THE REMAINDER BEING SAID OTHER SPECIFIED OXIDES WITHIN THE PROPORTION SPECIFIED, MOLDING SAID POWDER COMPOSITION, FIRING THE MOLDED BODY AT ABOUT 1180*C. TO ABOUT 1400*C., AND THEREAFTER SLOWLY COOLING THE FIRED BODY FROM 700*C. DOWN TO ROOM TEMPERATURE OVER A PERIOD OF AT LEAST ABOUT 12 HOURS TO PROVIDE A FERRITE BODY HAVING A CONSTRICTED HYSTERESIS LOOP, SAID FERRITES BEING RESPONSIVE TO THERMOMAGNETIC TREATMENT TO ALTER THE HYSTERESIS LOOP CHARACTERISTICS.