Ferrites, which can be classified as soft and hard ferrites, are oxide ceramic materials with the general composition MIIO•Fe2O3, which contain permanent magnetic dipoles. The special magnetic properties are due to the spontaneous parallel or inverse parallel position of the magnetic moments of the atoms in larger areas.
A multitude of magnetically soft materials of the composition MIIO•Fe2O3 is known today, where M = Fe can be Ni, Co, Mn, Mg, Cu, Ti, Cd or Zn. In practice however, two mixed ferrites have proven to be of particular value: manganese-zinc and nickel-zinc ferrites. The addition of zinc-ferrites enables systematic manipulation of the magnetic properties of a material.
Typical applications for soft ferrites:
- Core material for inductors and transformers in power electronics
- Ferrite antennae in radio, television, data and telecommunications technology
- Magnetic audio heads or magnetic amplifiers
- Ferrite cores for core memory in electronic data processing equipment
- Switching elements in microwave engineering
Since their introduction in the early 1950s, permanent ceramic ferrite magnets have steadily gained in importance. They are the most economical and most prevalent of all magnetic materials worldwide. Some of the most important hard ferrites are barium ferrite, strontium ferrite and the barium-strontium mixed ferrites.
Typical applications for hard ferrites are found in:
- Industrial electronics
- Sensor technology
- Television and radio technology
- Loudspeaker magnets
- Magnetic clamps, adhesive magnets or toy magnets
- Ring magnets or segment magnets in motors and generators for magnetic clutches
- Automotive industry, automotive engineering
- Clock and watch industry
- Household appliances, refrigerator seals
- Rotors for direct current motors