Ferrites having rectangular hysteresis loops and method for manufacture of same

Claim 1

A FERRITE FORMED OF A COMPOSITION CONSISTING ESSENTIALLY OF 30-48 MOL PERCENT IRON OXIDE, 10-45 MOL PERCENT MANGANESE IN THE FORM OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF MAGANOUS OXIDE, MANGANOUS MAGANIC OXIDE, MANGANESE DIOXIDE, MANGANESE CARBONATE AND COMPOUNDS REDUCIBLE TO AN OXIDE AT ELEVATED TEMPERATURE, 10-40 MOL PERCENT MAGNESIUM IN THE FORM OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM OXIDE, MAGNESIUM CARBONATE AND COMPOUNDS REDUCIBLE TO AN OXIDE AT ELEVATED TEMPERATURE, AND 3-15 MOL PERCENT ZINC IN THE FORM OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ZINC CARBONATE, ZINC OXIDE AND COMPOUNDS REDUCIBLE TO A ZINC OXIDE AT ELEVATED TEMPERATURE, SAID FERRITE HAVING BEEN PRODUCED BY THE STEPS OF MIXING THE MATERIALS IN FINELY DIVIDED FORM, MOLDING THE MIXED MATERIALS TO A DESIRED SHAPE, FIRING THE MOLDED PRODUCT IN A FIRST FIRING STEP TO A TEMPERATURE WITHIN THE RANGE OF 2250-2500*F., COOLING THE MATERIAL SUBSEQUENT TO THE FIRST FIRING STEP, REHEATING THE MATERIAL IN A SECOND FIRING STEP TO A TEMPERATURE WITHIN THE RANGE OF 2500-2750*F., AND THEN COOLING THE FIRED MATERIAL TO ROOM TEMPERATURE UNDER SUBSTANTIALLY NONOXIDIZING CONDITIONS.