Neodymium is a chemical element with the symbol Nd and atomic number 60. It is a soft, silvery metal that tarnishes in air. It was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. The substance is present in significant quantities in monazite sand deposits and in the mineral bastnäsite.
History
The rare earth metal neodymium was discovered by the Austrian chemist Baron Karl Auer von Welsbach in Vienna in 1885. The scientist isolated a new substance (as well as the element praseodymium) from a material known as didymium by fractional crystallization of double ammonium nitrate tetrahydrate from nitric acid, after separation by spectroscopic analysis. However, until 1925 it was not possible to obtain the element in its purest form.
Until the late 1940s, the main commercial method for producing metal was the double crystallization of nitrates. The method is ineffective, and the amount of the substance obtained was small. Lindsay Chemical Division was the first to start large-scale production of neodymiumion-exchange purification method. Since the 1950s, the highly purified (above 99%) element has been mainly produced by an ion exchange process from rare earth rich monazite by electrolysis of its halide s alts.
Currently, most metallic neodymium is extracted from bastnäsite. Advances in technology and the development of improved cleaning methods have made it widely used in industry.
Description
The chemical element does not occur naturally in a metallic form, it is separated from the substance didymium, 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, occurring at least as often as cob alt, nickel, or copper, and is widely distributed in the earth's crust. Most of the substance comes from China.
Neodymium compounds were first used commercially as glass colorants in 1927 and remain a popular additive in spectacle lenses. The color of neodymium compounds due to the presence of Nd3+ ions often has a reddish-purple tint, but this varies depending on the type of lighting.
Application
Ndodymium-doped lenses are used in lasers that emit infrared radiation with wavelengths between 1047 and 1062 nanometers. They are used in systems with extremely high power, for example, in experiments on inertialcontainment.
Nd:metal is also used with other crystals (such as yttrium aluminum garnet) in Nd:YAG lasers. This setup typically emits infrared rays with a wavelength of around 1064 nm. It is one of the most commonly used solid state lasers.
Another important use of neodymium metal is as a reinforcing component in alloys used to make 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 low magnetic mass (volume) or strong magnetic fields are required.
Large neodymium magnets are used in high power and weight electric motors (eg hybrid cars) and generators (eg aircraft and wind farm electrical generators). Also, the element is used to harden some alloys. For example, titanium becomes one and a half times stronger after adding just 1.5% of this substance.
Physical properties
Metallic neodymium is present in classic mischmetal (an alloy of rare earth elements), where its concentration is usually on the order of 18%. In its pure form, the element has a bright silver-gold metallic luster, but quickly oxidizes in ordinary air. An oxide layer forms and flakes off, exposing the metal to further oxidation. Thus,centimeter sample of the substance is completely oxidized within a year.
Neodymium usually exists in two allotropic forms, with a center-to-center transformation from a double hexagonal cubic structure. It begins to melt at 1024°C and boil at 3074°C. The density of matter in the solid phase is 7.01 g/cm3, in the liquid state is 6.89 g/cm3.
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.
- Radius of an atom: 181 picometers.
Chemical properties
Metal neodymium tarnishes slowly in air and burns easily at around 150°C to form neodymium(III) oxide:
4Nd + 3O2 → 2Nd2O3
This is an electropositive element. It reacts slowly with cold water, but rather quickly with hot water, forming neodymium (III) hydroxide:
2Nd(s) + 6H2O(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
Neodymium metal never occurs as a free element in nature. It is mined from ores such asbastnäsite and monazite, in which it is associated with other lanthanides and other elements. The main mining areas for these minerals are in China, the USA, Brazil, India, Sri Lanka and Australia. Small deposits have also been explored in Russia.
Reserves of neodymium are estimated at about 8 million tons. Its concentration in the Earth's crust is about 38 mg/kg, which is the second highest among the rare earth elements after cerium. World metal production is about 7000 tons. The main part of production belongs to China. The PRC government recently recognized the element as strategically important and imposed restrictions on its export, causing some concern in consumer countries and provoking a sharp increase in the price of neodymium 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 value of the metal fell to $40 due to illegal trade, bypassing the restrictions of the Chinese government. Pricing and availability uncertainties have led Japanese companies to develop permanent magnets and related electric motors with fewer or no rare earth elements.
