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A stack of ferrite magnets, with magnetic household items stuck to it. A ferrite is one of a family of iron oxide-containing magnetic ceramic materials. They are ferrimagnetic, meaning they are attracted by magnetic fields and can be magnetized to become permanent magnets.
Below the magnetization compensation point, ferrimagnetic material is magnetic. At the compensation point, the magnetic components cancel each other, and the total magnetic moment is zero. Above the Curie temperature, the material loses magnetism. Ferrimagnetism has the same physical origins as ferromagnetism and antiferromagnetism.
Ferromagnetic materials can be divided into magnetically soft materials (like annealed iron), which do not tend to stay magnetized, and magnetically hard materials, which do. Permanent magnets are made from hard ferromagnetic materials (such as alnico) and ferrimagnetic materials (such as ferrite) that are subjected to special processing in a ...
The ferrite magnets are mainly low-cost magnets since they are made from cheap raw materials: iron oxide and Ba- or Sr-carbonate. However, a new low cost magnet, Mn–Al alloy, [38] [non-primary source needed] [44] [45] has been developed and is now dominating the low-cost magnets field.
Ferrite nanoparticles or iron oxide nanoparticles (iron oxides in crystal structure of maghemite or magnetite) are the most explored magnetic nanoparticles up to date.Once the ferrite particles become smaller than 128 nm [22] they become superparamagnetic which prevents self agglomeration since they exhibit their magnetic behavior only when an external magnetic field is applied.
The composition of a typical ferrofluid is about 5% magnetic solids, 10% surfactant and 85% carrier, by volume. [ 9 ] Particles in ferrofluids are dispersed in a liquid, often using a surfactant , and thus ferrofluids are colloidal suspensions – materials with properties of more than one state of matter.
Barium ferrite is a common material for speaker magnets. The materials can be formed into almost any shape and size using a process called sintering, whereby powdered barium ferrite is pressed into a mold, and then heated until it fuses together. The barium ferrite turns into a solid block while still retaining its magnetic properties.
Ferromagnetic materials (like iron) are composed of microscopic regions called magnetic domains, that act like tiny permanent magnets that can change their direction of magnetization. Before an external magnetic field is applied to the material, the domains' magnetic fields are oriented in random directions, effectively cancelling each other ...