Ferrite is also called iron oxide or magnetic porcelain. It is a type of non-metallic magnetic material. It is a composite oxide (or ferrite) of magnetic iron oxide and other one or more metal oxides. Ferrites are magnetic and have a higher magnetic permeability (higher than metal magnetic materials) at high frequencies; their electrical resistivity is much larger than metal magnetic materials, and they have higher dielectric properties.
Ferrite magnetic materials can be divided into soft magnetic, hard magnetic, gyromagnetic and moment magnetic according to their coercive force (the strength of the external magnetic field that must be added to the direction of the original magnetization must be added to make the magnetized ferromagnetic material lose its magnetism) 5. Five types of magnetism. Soft ferrite is easy to be magnetized and demagnetized under a weak magnetic field, such as manganese-zinc ferrite Mn-ZnFe2O4 and nickel-zinc ferrite Ni-ZnFe2O4, the structure is spinel type; mainly for various inductive components, such as filtering The magnetic core of the device, transformer, antenna, etc. and the magnetic head of the recording and video recorder. Hard magnet ferrite is not easy to demagnetize after magnetization, and can retain magnetism for a long time, such as barium ferrite BaFe12O17, the structure is mostly magnetoplumbite type; mainly used as a constant magnetic source, can replace aluminum in telecommunications, electroacoustics, electric meters, motor industry Nickel-cobalt hard magnetic metal material. Rotating ferrite is also called microwave ferrite, such as nickel-copper ferrite Ni-CuFe2O4 and yttrium garnet ferrite 3M2O3·5Fe2O3 (M is trivalent yttrium, samarium, yttrium and other rare earth ions), used for radar, In electronic devices such as navigation and remote control. Moment ferrite has a rectangular hysteresis loop, such as lithium manganese ferrite Li-MnFe2O4, etc., generally used as a memory element, used in electronic computer memory. When the ferrite magnet is magnetized, it can be mechanically extended or compressed in the direction of the magnetic field, such as nickel-zinc ferrite Ni-ZnFe2O4, nickel-copper ferrite Ni-CuFe2O4, etc. It is generally used as a magnetostrictive element for ultrasonic energy conversion etc.