Ferrite can be divided into permanent ferrite, hard magnetic material, gyromagnetic material, rectangular magnetic material and piezomagnetic material. According to the above classification, the application scope and performance of various ferrites are described as follows:
Permanent magnet ferrite
Compounds with uniaxial anisotropy and hexagonal structure. Mainly barium, strontium, lead ferrite and their composite solid solutions. There are two kinds of magnetism: same-sex magnetism and opposite-sex magnetism. Because this kind of ferrite material can keep strong constant remanence characteristics for a long time after the external magnetization field disappears, it can be used to generate a constant magnetic field in outer space. For example, it is widely used as a permanent magnet in various electric meters, generators, telephones, speakers, televisions and microwave equipment.
Hard magnetic material
Ferrite hard magnetic material is not easy to demagnetize after magnetization, so it is also called permanent magnetic material or permanent magnetic material. Such as barium ferrite and steel ferrite. Mainly used in recording equipment, pickups, speakers, magnetic cores of various instruments, etc.
Gyromagnetic material
The gyromagnetic characteristics of magnetic materials refer to the phenomenon that under the action of two vertical steady magnetic fields and electromagnetic fields, the plane polarized electromagnetic waves propagate in a certain direction inside the material, but the polarization plane will rotate around the propagation direction. Although metal and alloy materials also have certain gyromagnetic characteristics, electromagnetic waves cannot penetrate them because of their low resistivity and large eddy current loss. Therefore, the application of ferrite gyromagnetic materials has become a unique field of ferrite. Most gyromagnetic materials and waveguides or transmission lines that transmit microwaves form various microwave devices. Mainly used in radar, communication, navigation, telemetry and other electronic equipment.
Magnetic moment magnetic material
This refers to ferrite materials with rectangular hysteresis loops. Its characteristic is that when there is a small external magnetic field, it can be magnetized and saturated. After removing the external magnetic field, the magnetism remains the same as when saturated. Such as magnesium manganese ferrite, lithium manganese ferrite, etc. This ferrite material is mainly used for storage cores of various electronic computers.
Piezomagnetic material
This kind of material refers to ferrite materials that are mechanically elongated or shortened along the direction of magnetic field when magnetized, such as nickel-zinc ferrite, nickel-copper ferrite, nickel-chromium ferrite and so on. Piezoelectric materials are mainly used as transducers for mutual conversion between electromagnetic energy and mechanical energy, and as magnetostrictive elements for ultrasonic waves.