Barium ferrite Barium ferrite Barium ferrite, abbreviated BaFe, BaM, is the chemical compound with the formula BaFeO. This and related ferrite materials are components in magnetic stripe cards and loudspeaker magnets. BaFe is described as Ba(Fe)(O). The Fe centers are ferromagnetically coupled. 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,
Brass percentages of nickel, lead and iron. During the later part of first millennium BC the use of brass spread across a wide geographical area from Britain and Spain in the west to Iran, and India in the east. This seems to have been encouraged by exports and influence from the Middle East and eastern Mediterranean where deliberate production of brass from metallic copper and zinc ores had been introduced. The 4th century BC writer Theopompus, quoted by Strabo, describes how heating earth from Andeira in Turkey produced "droplets of false silver", probably metallic zinc, which could be used to turn