Patent ID: 7326360

Claim:
A method for making metal-substituted cobalt ferrite comprising the steps of: mixing oxides or carbonates of Fe, Co, and M in the targeted proportions to form a mixed powder, where M is selected from the group consisting of Mn, Cr, Zn, Al, Cu, and any mixtures thereof; pressing the mixed powder, calcining the mixed powder at a temperature in the range of approximately 900° C. to 1200° C. for a period of time ranging from about 2 to about 24 hours in air; ball milling the mixed powder to less than 38 micron powder; pressing and calcining the mixed powder at a temperature in the range of approximately 900° C. to 1200° C. for a period of time ranging from about 2 to about 24 hours in air; remilling the mixed powder to less than 38 micron powder; mixing the mixed powder and forming the mixed powder into a desired shape; and sintering the mixed powder at a temperature in the range of approximately 1000° C. to 1350° C. for a period of time ranging from about 2 to about 24 hours in air, thereby forming the metal-substituted cobalt ferrite.