Barium ferrite

Barium ferrite, abbreviated BaFe, BaM, is the chemical compound with the formula This area of technology is usually considered to be an application of the related fields of materials science and solid state chemistry. Barium ferrite is a highly magnetic material, has a high packing density, and is a metal oxide. Studies of this material date at least as far back as 1931, and it has found applications in magnetic card strips, speakers, and magnetic tapes.

Barium ferrite has been considered for long term data storage. The material has proven to be resistant to a number of different environmental stresses, including humidity and corrosion. Because ferrites are already oxidized it can not be oxidized any further. This is one reason ferrites are so resistant to corrosion. Barium ferrite also proved to be resistant to thermal demagnetization, another issue common with long term storage.

Barium ferrites are robust ceramics that are generally stable to moisture and corrosion resistant.

Barium ferrite is used in applications such as recording media, permanent magnets, and magnetic stripe cards (credit cards, hotel keys, ID cards). Due to the stability of the material, it is able to be greatly reduced in size, making the packing density much greater. Earlier media devices utilized doped acicular oxide materials to yield the coercivity values necessary to record. In recent decades, barium ferrite has replaced acicular oxides; without any dopants, the acicular oxides produce very low coercivity values, making the material very magnetically soft, while barium ferrite's higher coercivity levels make the material magnetically hard and thus a superior choice for recording material applications.

ID cards using barium ferrite are made with a magnetic fingerprint that identifies them, allowing readers to self calibrate.

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. The magnets have an excellent resistance to demagnetization, allowing them to still be useful in speaker units over a long period of time.

Barium ferrite is used for enterprise level and commodity linear tape open (LTO) tape storage media. Because of its high density, barium ferrite has led to data capacity improvements in both enterprise and LTO tapes over prior metal particle (MP) media technology. Developments in the field have also resulted in the reduction of the size of BaFe particles to about 20 nm. This contrasts with MP technology, which has problems shrinking the particles past 100 nm.