Technology 2000

Neodymium: very interesting material

Neodymium is a chemical element with the symbol Nd and atomic number 60. It is a soft silvery metal that tarnishes in air.
Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. It is present in significant quantities
in the ore minerals monazite and bastnäsite. Neodymium is not found naturally in metallic form or unmixed with other lanthanides,
and it is usually refined for general use. Although neodymium is classed as a "rare earth", it is a fairly common element, no rarer than cobalt,
nickel, and copper, and is widely distributed in the Earth's crust.Most of the world's neodymium is mined in China.(where?)
Neodymium compounds were first commercially used as glass dyes in 1927, and they remain a popular additive in glasses.
The color of neodymium compounds—due to the Nd3+ ion—is often a reddish-purple but it changes with the type of lighting,
due to fluorescent effects. Some neodymium-doped glasses are also used in lasers that emit infrared light with wavelengths between 1047 and 1062 nanometers.
These have been used in extremely high power applications, such as experiments in inertial confinement fusion.
Neodymium is also used with various other substrate crystals, such as yttrium aluminum garnet in the Nd:YAG laser.
This laser usually emits infrared waves at a wavelength of about 1064 nanometers. The Nd:YAG laser is one of the most commonly used solid-state lasers.
Another chief use of neodymium is as the free pure element. It is used as a component in the alloys used to make high-strength neodymium magnets – powerful permanent magnets
These magnets are widely used in such products as microphones, professional loudspeakers, in-ear headphones, and computer hard disks
, where low magnet mass or volume, or strong magnetic fields are required. Larger neodymium magnets are used
in high power versus weight electric motors (for example in hybrid cars) and generators (for example aircraft and wind turbine electric generators).

History of neodynium

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 fractional crystallization of the double ammonium nitrate tetrahydrates from nitric acid, while following
the separation by spectroscopic analysis; however, it was not isolated in relatively pure form until 1925.
The name neodymium is derived from the Greek words neos and didymos
Double nitrate crystallization was the means of commercial neodymium purification until the 1950s.
Lindsay Chemical Division was the first to commercialize large-scale ion-exchange purification of neodymium.
Starting in the 1950s, high purity (above 99%) neodymium was primarily obtained through an ion exchange process from monazite,
a mineral rich in rare earth elements. The metal itself is obtained through electrolysis of its halide salts. Currently, most neodymium is extracted from bastnäsite,
(Ce,La,Nd,Pr)CO3F, and purified by solvent extraction. Ion-exchange purification is reserved for preparing the highest purities (typically >99.99%).
The evolving technology, and improved purity of commercially available neodymium oxide, was reflected in the appearance of neodymium glass that resides
in collections today. Early neodymium glasses made in the 1930s have a more reddish or orange tinge than modern versions which are more cleanly purple,
due to the difficulties in removing the last traces of praseodymium in the era when manufacturing relied upon fractional crystallization technology.

PRODUCTION OF NEODYNIUM

Neodymium is never found in nature as the free element, but rather it occurs in ores such as monazite and bastnäsite that contain small amounts of all the rare earth metals.
The main mining areas are in China, the United States, Brazil, India, Sri Lanka, and Australia. The reserves of neodymium are estimated at about eight million tonnes.
Although it belongs to the rare earth metals, neodymium is not rare at all. Its abundance in the Earth crust is about 38 mg/kg,
which is the second highest among rare-earth elements, following cerium. The world's production of neodymium was about 7,000 tonnes in 2004.
The bulk of current production is from China, whose government has recently imposed strategic materials controls on the element,
raising some concerns in consuming countries and causing skyrocketing prices of neodymium and other rare-earth metals.
As of late 2011, 99% pure neodymium was traded in world markets for US$300–350 per kilogram, down from the mid-2011 peak of 500 dollard/kg.
Neodymium is typically 10–18% of the rare earth content of commercial deposits of the light rare earth element minerals bastnasite and monazite
With neodymium compounds being the most strongly colored for the trivalent lanthanides, that percentage of neodymium can occasionally dominate the coloration
of rare earth minerals—when competing chromophores are absent. It usually gives a pink coloration. Outstanding examples of this include monazite crystals from
the tin deposits in Llallagua, Bolivia; ancylite from Mont Saint-Hilaire, Quebec, Canada; or lanthanite from the Saucon Valley, Pennsylvania, US.
As with neodymium glasses, such minerals change their colors under the differing lighting conditions. The absorption bands of neodymium interact
with the visible emission spectrum of mercury vapor, with the unfiltered shortwave UV light causing neodymium-containing minerals to reflect a distinctive green color.
This can be observed with monazite-containing sands or bastnasite-containing ore