Barium permanent magnet

Barium carbonate of finely controlled particle size reacts in the soHd state when heated with iron oxide to form barium ferrites. Magnetically aligned barium ferrite [11138-11-7] powder can be pressed and sintered into a hard-core permanent magnet which is used in many types of small motors. Alternatively, ground up magnetic powder can be compounded into plastic strips which are used in a variety of appHances as part of the closure mechanism. 

FERROELECTRIC EFFECT. The phenomenon whereby certain crystals may exhibit a spontaneous dipole moment twhich is called ferroelectric by analogy with ferromagnetic—exhibiting a permanent magnetic moment). The effect in the most typical case, barium manate. seems to he due to a polarization catastrophe, in which the local electric fields due lo the polarizuiion itself increase faster than die elastic restoring forces on the ions in Ihe crystal, thereby leading to an asymmetrical shift in ionic positions, and hence lo a permanent dipole moment. Ferroelectric crystals... 

Barium ferrite adequate for certain permanent magnet applications can be prepared from crude mineral iron oxide. A past interest in the material for perpendicular magnetic recording stimulated studies of a variety of chemical routes, including hydrothermal synthesis, to produce powders [12]. 

Barium hexaferrite. Barium hexaferrite, BaFei20 <<, is used as a ceramic permanent magnet. It is conventionally prepared by firing an appropriate mixture of a-Fe203 with BaCOs at high temperatures (1150-1250°C). To reduce the particle size, thus obtained ferrite should be ground. 

Barium ferrite is used in permanent magnets owing to the strong magnetic interaction of the unpaired electrons of the iron ions in the lattice... 

The ferromagnetic material barium hexaferrite, BaFe Oig, also known as BaM, is an important component in permanent magnets [270], It can be prepared by the MOCVD of a mixture of [Ba(thd)2]4 (thd" 7) and ferrocene, Cp2Fe [273]. 

Magnaplas. [Bay Resins] Nylon 6, barium ferrite-filled permanent magnetic material. 

The reader probably knows already that real motors have more coils and poles, and more complex commutators. There is more than one pulse of attraction, and sometimes the current is reversed to also cause repulsion. The coil almost always has a small soft iron core, and the permanent magnet is a large piece of hard steel or ferrite (iron oxide and barium oxide ceramic). Because the permanent magnet is heavier than the coil, it is usually the stationary part, not the way it is shown here. However, this diagram communicates the main ideas. 

Barium Carbonate. BaC03, decomposes at 1450°C sp. gr. 4.4. Occurs naturally in Durham, England, as witherite. The principal use in the ceramic industry of the raw material is for the prevention of efflorescence on brickwork for this purpose it is added to brick-clays containing soluble sulphates. The pure material is used in the manufacture of barium ferrite permanent magnets, and in some ceramic dielectrics to give lower dielectric loss. In the glass industry this compound is used in optical glass and television tubes it is also used in some enamel batches. 

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