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Neodymium
magnets are a member of the rare-earth magnet family. They are
called "rare earth" because neodymium
is
a member of the "rare earth" elements on the periodic table.
Neodymium magnets
are
the strongest of the rare earth magnets and are the
strongest
permanent magnets available in the world.
Neodymium
magnets are actually composed of neodymium, iron and boron (they are
also referred to as NIB magnets). The powdered mixture is
pressed under great pressure into molds. The material is then
sintered (heated under a vacuum), cooled, and then ground or sliced
into the desired shape. Coatings are applied (optional).
Finally, the blank magnets are magnetized by exposing them to an
extremely powerful magnetic field.
Neodymium,
atomic no.: 60, symbol as Nd, weight at 144.24,
is the most abundant of the rare earths after cerium and lanthanum.
It shows similar characteristics to the other trivalent lanthanides.
Primary applications include lasers, glass coloring and tinting,
dielectrics and, most importantly, as the fundamental basis for
neodymium-iron-boron (Nd2Fe14B) permanent
magnets.
The neodymium-based magnet was first introduced in 1982
simultaneously by Sumitomo Specialty Metals (Japan) and General
Motors (USA) and commercialized in 1986. It is used extensively in
the automotive industry with many applications including starter
motors, brake systems, seat adjusters and car stereo speakers. Its
largest application is in the voice coil motors used in computer
disk drives.
Neodymium has a strong absorption band centered at 580 nm,
which is very close to the human eye's maximum level of sensitivity
making it useful in protective lenses for welding goggles. It is
also used in CRT displays to enhance contrast between reds and
greens. It is highly valued in glass manufacturing for its
attractive purple coloring to glass.
Neodymium is included in
many formulations of barium titanate, used as dielectric coatings
and in multi-layer capacitors essential to electronic equipment.
Yttrium-aluminum-garnet (YAG) solid-state lasers utilize
neodymium because it has optimal absorption and emitting
wavelengths. Nd-based YAG lasers are used in various medical
applications, drilling, welding and material processing.
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