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Magnetic materials

Stan Zurek, Magnetic materials, Encyclopedia-Magnetica.com, {accessed 2021-03-01}

Magnetic materials - a term commonly used to refer to materials, which exhibit strong magnetic effects, such as ferromagnetic or ferrimagnetic. Either of the two can also exhibit properties which are magnetically soft, hard, or semihard.1)

However, in general all materials are “magnetic” but they respond in various ways to magnetic field, depending on their atomic structure and ambient conditions, or at least do not significantly obstruct magnetic field. In that sense, even vacuum is “magnetic” because magnetic field can propagate through it and by definition its magnetic permeability $μ_0$ is a universal physical constant in the SI system of units.2)


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Efficient energy transformation relies on magnetic materials The Taza power plant, photographed Nov. 2, 2008, in Kirkuk, Iraq, is the largest
and newest power plant in Kirkuk province.  The V94 turbine generator generates
electricity for the Northern regions of Iraq. (U.S. Army photo by Sgt. 1st Class... Marvin L. Daniels, Public domain
Permanent magnets are capable of retaining a large amount of magnetic energy hard_ferrites_1_magnetica.jpg

S. Zurek, Encyclopedia Magnetica, CC-BY-4.0

Magnetic field penetrating “nonmagnetic” vacuum can bend the path of moving electrons into a circle ASCII by M. Białek, Wikimedia Commons, CC-BY-SA-3.0

Magnetic properties of all pure chemical elements of practical importance were measured, with at least an order-of-magnitude accuracy (see the large illustration with the periodic table below). The elements can be broadly classified into diamagnetic and paramagnetic (weak magnetic properties) and ferromagnetic (strong magnetic properties). At room temperature only three elements are ferromagnetic: iron, cobalt, and nickel.

However, pure elements are rarely used because of their magnetic properties (but they can be used for other reasons, like for instance copper for making electric wires or noble gases for providing protective chemical atmosphere).

From engineering viewpoint, metal alloys and chemical compounds, even made from non-ferromagnetic elements, can exhibit very strong magnetic effects, which need to be tailored, by many means: chemical composition, mechanical forming, thermal processing (annealing), with or without magnetic field.

Periodic table of elements, with magnetic properties3) (at very low temperatures, and also high pressure, many elements become superconducting and hence strongly diamagnetic)

S. Zurek, Encyclopedia Magnetica, CC-BY-4.0

There are several ways in which materials can respond, and these different types of response are described by various types of magnetism:

See also

References

magnetic_materials.txt · Last modified: 2020/12/07 00:07 by stan_zurek

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