Neodymium is a chemical element with the symbol Nd and atomic number 60. It is a soft silver metal that dims in air. It was discovered in 1885 by the Austrian chemist Karl Auer von Welsbach. The substance is present in significant quantities in deposits of monazite sand and a mineral such as bastnesite.
History
Rare earth metal neodymium was discovered by Austrian chemist Baron Karl Auer von Welsbach in Vienna in 1885. The scientist isolated a new substance (as well as the praseodymium element) from a material known as didyme by fractional crystallization of double tetrahydrate of ammonium nitrate from nitric acid, after separation by spectroscopic analysis. However, until 1925 it was not possible to obtain the element in a pure form.
Until the end of 1940, the main commercial method for producing metal was double crystallization of nitrates. The method is ineffective, and the amount of substance obtained was small. Lindsay Chemical Division was the first to start large-scale production of neodymium by ion exchange purification. Since the 1950s, a highly purified (above 99%) element is mainly obtained as a result of the ion exchange process from monazite, rich in rare earth elements, by electrolysis of its halide salts.
Currently, most metallic neodymium is extracted from bastnesite. Developing technologies and the development of improved cleaning methods have made it widely used in industry.
Description
The chemical element does not naturally occur in metallic form, it is separated from the substance didim, in which it is mixed with other lanthanides (in particular, with praseodymium). Although neodymium is classified as a rare earth metal, it is a fairly common element that occurs no less than cobalt, nickel or copper, and is widespread in the earth's crust. Most of the substance is mined in China.
Neodymium compounds were first used commercially as glass dyes in 1927, and they remain a popular additive in spectacle lenses. The color of neodymium compounds due to the presence of Nd 3+ ions often has a reddish-violet hue, but it varies depending on the type of lighting.
Application
Neodymium-doped lenses are used in lasers emitting infrared radiation with a wavelength of 1047 to 1062 nanometers. They are used in systems with extremely high power, for example, in inertial containment experiments.
Metallic neodymium is also used with other crystals (such as yttrium aluminum garnet) in Nd: YAG lasers. This installation usually emits infrared rays with a wavelength of about 1064 nm. It is one of the most commonly used solid-state lasers.
Another important use of metallic neodymium is as a reinforcing component in alloys used for the manufacture of powerful high-strength permanent magnets. They are widely used in products such as microphones, professional loudspeakers, in-ear headphones, high-performance DC motors, computer hard drives - where small magnetic mass (volume) or strong magnetic fields are required.
Large neodymium magnets are used in electric motors with high power and weight (for example, in hybrid cars), and generators (for example, electric generators of aircraft and wind power stations). Also, the element is used to harden some alloys. For example, titanium becomes one and a half times stronger after the addition of only 1.5% of this substance.
Physical properties
Metallic neodymium is present in the classic mischmetal (an alloy of rare-earth elements), where its concentration is usually about 18%. In its pure form, the element has a bright silver-golden metallic luster, but is quickly oxidized in ordinary air. An oxide layer forms which peels off, subjecting the metal to further oxidation. Thus, a centimeter sample of the substance is completely oxidized within a year.
Neodymium usually exists in two allotropic forms with conversion from a double hexagonal cubic structure from center to center. It begins to melt at 1024 ° C, and begins to boil at 3074 ° C. The density of the substance in the solid phase is 7.01 g / cm 3 in the liquid state is 6.89 g / cm 3 .
Atomic properties:
- Oxidation state: +4, +3, +2 (basic oxide).
- Electronegativity: 1.14 (Polling scale).
- Thermal conductivity: 16.5 W / (m · K).
- Ionization energy: 1: 533.1 kJ / mol, 2: 1040 kJ / mol, 3: 2130 kJ / mol.
- Atom radius: 181 picometers.
Chemical properties
Metallic neodymium slowly fades in air and burns easily at a temperature of about 150 ° C with the formation of neodymium oxide (III):
4Nd + 3O 2 → 2Nd 2 O 3
This is an electropositive element. It slowly reacts with cold water, but rather quickly - with hot, forming neodymium (III) hydroxide:
2Nd (s) + 6H 2 O (l) → 2Nd (OH) 3 (aq) + 3H 2 (g)
The metal reacts vigorously with all halogens, easily dissolves in dilute sulfuric acid to form solutions that contain the violet Nd (III) ion.
Production
Metallic neodymium is never found in nature as a free element. It is mined from ores such as bastnesite and monazite, in which it is associated with other lanthanides and other elements. The main areas of extraction of these minerals are in China, the USA, Brazil, India, Sri Lanka and Australia. Small deposits have been explored in Russia.
Neodymium reserves are estimated at approximately 8 million tons. Its concentration in the Earth's crust is about 38 mg / kg, which is the second largest among rare earths after cerium. World metal production is about 7,000 tons. The bulk of the production belongs to China. The PRC government recently recognized the element as strategically important and imposed restrictions on its export, raising some concerns in consumer countries and provoking a sharp rise in neodymium prices to $ 500. Today, the average price per kilogram of pure metal varies between $ 300-350, neodymium oxides are cheaper: $ 70-130.
There are cases when the cost of metal fell to $ 40 due to illegal trade, bypassing the restrictions of the Chinese government. Uncertainty in pricing and affordability has forced Japanese companies to develop permanent magnets and related motors with fewer or fewer rare earths.