Neodymium

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Neodymium

Neodymium is a chemical element in the periodic table that has the symbol Nd and atomic number 60.

Notable characteristics

Neodymium, a rare earth metal, is present in misch metal to the extent of about 18%. The metal has a bright silvery metallic luster; however, being one of the more reactive rare-earth metals, neodymium quickly tarnishes in air, forming an oxide that falls off and exposes the metal to further oxidation.

Applications

Uses of neodymium include:

Neodymium is a component of didymium used for colouring glass to make welder's goggles.
Neodymium colours glass in delicate shades ranging from pure violet through wine-red and warm grey. Light transmitted through such glass shows unusually sharp absorption bands; the glass is used in astronomical work to produce sharp bands by which spectral lines may be calibrated. Neodymium is also used to remove the green colour caused by iron contaminants from glass.
Neodymium salts are used as a colourant for enamels.
Neodymium is used in very powerful permanent magnets - Nd₂Fe₁₄B. These magnets are cheaper, lighter, and stronger than samarium-cobalt magnets. Neodymium magnets appear in high-quality products such as microphones, professional loudspeakers, in-ear headphones and computer hard disks where low weight, reduced size or powerful magnets are required.
Certain transparent materials with a small concentration of neodymium ions can be used in lasers as gain media for infrared wavelengths (1054-1064 nm), e.g. YAG (yttrium aluminium garnet), Nd:YLF (yttrium lithium fluoride), Nd:YVO₄ (yttrium orthvanadate), and Nd:glass.

Probably because of similarities to Ca²⁺, Nd³⁺ has been reported ^* to promote plant growth. Rare earth element compounds are frequently used in China as fertilizer.

History

Neodymium was discovered by Baron Carl Auer von Welsbach, an Austrian chemist, in Vienna in 1885. He separated neodymium, as well as the element praseodymium, from a material known as didymium by means of spectroscopic analysis; however, it was not isolated in relatively pure form until 1925. The name neodymium is derived from the Greek words neos, new, and didymos, twin.

Today, neodymium is primarily obtained through an ion exchange process of monazite sand ((Ce,La,Th,Nd,Y)PO₄), a material rich in rare earth elements, and through electrolysis of its halide salts.

Occurrence

Neodymium is never found in nature as the free element; rather, it occurs in ores such as monazite sand ((Ce,La,Th,Nd,Y)PO₄) and bastnasite ((Ce,La,Th,Nd,Y)(CO₃)F) that contain small amounts of all the rare earth metals. Neodymium can also be found in Misch metal; it is difficult to separate it from other rare earth elements.

Compounds

Neodymium compounds include:

Fluorides
- NdF₃
Chlorides
- NdCl₂
- NdCl₃
Bromides
- NdBr₂
- NdBrs₃
Iodides
- NdI₂
- NdI₃
Oxides
- Nd₂O₃
Sulfides
- NdS
- Nd₂S₃
Selenides
- NdSe
Tellurides
- NdTe
- Nd₂Te₃
Nitrides
- NdN

See also Neodymium compounds.

Isotopes

Naturally occurring Neodymium is composed of 5 stable isotopes, ¹⁴²Nd, ¹⁴³Nd, ¹⁴⁵Nd, ¹⁴⁶Nd and ¹⁴⁸Nd, with ¹⁴²Nd being the most abundant (27.2% natural abundance), and 2 radioisotopes, ¹⁴⁴Nd and ¹⁵⁰Nd. In all, 31 radioisotopes of Neodymium have been characterized, with the most stable being ¹⁵⁰Nd with a half-life (T_½) of >1.1×10¹⁹ years, ¹⁴⁴Nd with a half-life of 2.29×10¹⁵ years, and ¹⁴⁷Nd with a half-life of 10.98 days. All of the remaining radioactive isotopes have half-lives that are less than 3.38 days, and the majority of these have half-lives that are less than 71 seconds. This element also has 4 meta states with the most stable being ¹³⁹Nd^m (T_½ 5.5 hours), ¹³⁵Nd^m (T_½ 5.5 minutes) and ¹⁴¹Nd^m (T_½ 62.0 seconds).

The primary decay mode before the most abundant stable isotope, ¹⁴²Nd, is electron capture and the primary mode after is beta minus decay. The primary decay products before ¹⁴²Nd are element Pr (praseodymium) isotopes and the primary products after are element Pm (promethium) isotopes.

Precautions

Neodymium metal dust is a combustion and explosion hazard.

Neodymium compounds, like all rare earth metals, are of low to moderate toxicity; however its toxicity has not been thoroughly investigated. Neodymium dust and salts are very irritating to the eyes and mucous membranes, and moderately irritating to skin. Breathing the dust can cause lung embolisms, and accumulated exposure damages the liver. Neodymium also acts as an anticoagulant, especially when given intravenously.

Neodymium magnets have been tested for medical uses such as magnetic braces and bone repair, but biocompatibility issues have prevented widespread application.

References

Los Alamos National Laboratory - Neodymium

External links

Chemical elements | Lanthanides

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