||(Gr. neos, new, and didymos, twin) In 1841, Mosander, extracted from cerite a
new rose-colored oxide, which he believed contained a new element. He
named the element didymium, as it was an inseparable twin brother of
lanthanum. In 1885 von Welsbach separated didymium into two new
elemental components, neodymia and praseodymia, by repeated
fractionation of ammonium didymium nitrate. While the free metal is in
misch metal, long known and used as a pyrophoric alloy for light flints,
the element was not isolated in relatively pure form until 1925.
Neodymium is present in misch metal to the extent of about 18%. It is
present in the minerals monazite and bastnasite, which are principal
sources of rare-earth metals.
||The element may be obtained by separating
neodymium salts from other rare earths by ion-exchange or solvent
extraction techniques, and by reducing anhydrous halides such as NdF3
with calcium metal. Other separation techniques are possible.
||The metal has a bright silvery metallic
luster, Neodymium is one of the more reactive rare-earth metals and
quickly tarnishes in air, forming an oxide that spalls off and exposes
metal to oxidation. The metal, therefore, should be kept under light
mineral oil or sealed in a plastic material. Neodymium exists in two
allotropic forms, with a transformation from a double hexagonal to a
body-centered cubic structure taking place at 863oC.
||Natural neodymium is a mixture of seven
stable isotopes. Fourteen other radioactive isotopes are recognized.
||Didymium, of which neodymium is a
component, is used for coloring glass to make welders goggles. By
itself, neodymium colors glass delicate shades ranging from pure violet
through wine-red and warm gray. Light transmitted through such glass
shows unusually sharp absorption bands. The glass has been used in
astronomical work to produce sharp bands by which spectral lines may be
calibrated. Glass containing neodymium can be used as a laser material
to produce coherent light. Neodymium salts are also used as a colorant
||The price of the metal is about $1/g.
||Neodymium has a low-to-moderate acute
toxic rating. As with other rare earths, neodymium should be handled
Alamos National Laboratory