Ferrite is made of iron oxide and other ingredients sintered. Generally can be divided into permanent ferrite, soft ferrite and rotating ferrite three.
Permanent ferrite, also known as ferrite magnets, is what we usually see the black small magnet. The composition of raw materials mainly iron oxide, barium carbonate or strontium carbonate. After magnetization, the residual magnetic field is very high, and can keep the residual magnetic field for a long time. Usually used as permanent magnet material. For example: speaker magnet.
Soft ferrite is made of ferric oxide and one or several other metal oxides (such as: nickel oxide, zinc oxide, manganese oxide, magnesium oxide, barium oxide, strontium oxide, etc.) prepared by sintering. It is called soft magnetic, because when the magnetizing field disappears, the residual magnetic field is small or almost no. Usually used as choke, or IF transformer core. This is completely different from permanent magnet ferrite.
The rotating ferrite refers to a ferrite material having spin-magnetic properties. Magnetic properties of the magnetic material refers to the two vertical DC magnetic field and the role of electromagnetic waves under the action of the plane polarization of electromagnetic waves in the material within a certain direction of the process of transmission, the polarization plane will continue to spread around the propagation direction of the phenomenon  The Rotomagnetic ferrite has been widely used in the field of microwave communications. According to the type of crystal, the rotating ferrite can be divided into spinel type, garnet type and magnetite type (hexagonal) ferrite.
According to the different nature of magnetic properties and application of ferrite can be divided into: soft magnetic, permanent magnet, magnetic, magnetic, magnetic and other five types.
Soft magnetic material
Such materials in the weak magnetic field, easy to magnetize and easy demagnetization, such as zinc chrome ferrite and nickel zinc ferrite. Soft ferrite is the current use of wide, variety, large quantity, high output value of a ferrite material. It is mainly used as a variety of inductance components, such as filter core, transformer core, radio core, and tape recording and video head, etc., is also a key component of magnetic recording components.
A compound having a hexagonal structure with uniaxial anisotropy. Mainly barium, strontium, lead three ferrite and its composite solid solution. Homogeneous magnetic and heterosexual magnetic division. Because this kind of ferrite material disappears in the external magnetization field, it can still retain a strong constant remanent magnetization for a long time and can be used to generate a stable magnetic field to the external space. Its application is very broad, for example: in all kinds of meters, generators, telephones, speakers, televisions and microwave devices used as a constant magnet.
Hard magnetic material
Ferrite hard magnetic material is not easy to demagnetize magnetization, therefore, also known as permanent magnet material or constant magnetic material. Such as barium ferrite, steel ferrite and so on. It is mainly used in telecommunications devices in the sounders, pickups, speakers, a variety of instrument cores and so on.
Magnetic properties of the magnetic material refers to the two perpendicular to each other under the steady magnetic field and the role of electromagnetic waves, the plane polarization of electromagnetic waves in the material although a certain direction of transmission, but its polarization plane will continue to spread around the direction of rotation. Metal and alloy materials have a certain degree of magnetic properties, but because of low resistivity, eddy current loss is too large, electromagnetic waves can not penetrate its internal, it can not be used. Therefore, the application of ferrite rotating material magnetic properties, it has become a unique field of ferrite. Most of the magnetic material and the transmission of microwave waveguide or transmission line composed of a variety of microwave devices. Mainly used for radar, communications, navigation, telemetry and other electronic equipment.
Moment magnetic material
This refers to a ferrite material with a rectangular hysteresis loop. Its characteristic is that when there is a small external magnetic field, it can make it magnetized and reach saturation, remove the external magnetic field, the magnetic remains the same as when saturated. Such as magnesium manganese ferrite, lithium manganese ferrite, etc. is the case. This ferrite material is mainly used for a variety of electronic computer memory core and so on.
Such materials refer to ferrite materials that are mechanically elongated or shortened in the direction of magnetic field when magnetized, such as nickel-zinc ferrite, nickel-copper ferrite and nickel-chromium ferrite. Magnetostrictive materials are mainly used for electromagnetic energy and mechanical energy conversion of the transducer, for the magnetostrictive element for ultrasound.