Small ferromagnetic cores are strung or magnetic porcelain. As a kind of nonmetallic magnetic materials. Is magnetic ferric oxide and one or more other metal oxide composite oxide (or ferrite). Ferrite magnetic, will be higher in high frequency permeability (higher than that of metallic magnetic materials); its resistivity is much larger than the metallic magnetic materials, and high dielectric properties. Magnetite FeO · Fe2O3 is the simplest of ferrite. Usually ferrite by those with a d or f layer composed of unpaired electrons in the element, especially with ferrous iron ion RADIUS is close to that of Divalent metal ions, such as manganese, zinc, copper, nickel, cobalt, magnesium, plasma, or rare earth elements by ion or gallium, aluminum and bismuth, strontium, barium, and plasma.