Note: This article, originally published in 1998, was updated in 2006 for the eBook edition.
Neodymium was discovered in 1885 by Austrian chemist Carl Auer (Baron von Welsbach; 1858-1929). Auer found the new element in a mineral called didymia. Didymia, in turn, had been found in another complicated mineral known as ceria, originally found in Sweden in 1803. It took chemists nearly a century to completely analyze ceria. When they had done so, they found that it contained seven new elements. Neodymium was one of these.
Neodymium is in Row 6 of the periodic table. The periodic table is a chart that shows how chemical elements are related to each other. The elements in Row 6 are sometimes called the rare earth elements. The term "rare earth" is inaccurate, however. These elements are not especially rare but are difficult to separate from each other. The rare earth elements are also called the lanthanides. That name comes from the third element in Row 6, lanthanum.
Neodymium has long been used in coloring glass and is now used in making lasers, very powerful magnets, and special alloys.
(rare earth metal)
Discovery and naming
During the late 1700s, two important mineral discoveries were made in Sweden. One was made just outside the town of Ytterby. The mineral found there, yttria, was eventually found to contain nine new elements. The second discovery was made near the town of Bastnas. That mineral, called cerite, was later found to contain seven new elements.
Cerite was thoroughly studied by Swedish chemist Carl Gustav Mosander (1797-1858). In 1839, Mosander was able to separate cerite into two parts, which he called cerium and lanthanum. Mosander believed he had found two new elements. Two years later, however, he learned that lanthanum was not an element but a mixture of two parts. Mosander called these two new parts lanthanum and didymium. Mosander chose the name didymium because it means "twin." He said that didymium was like an identical twin to lanthanum. Chemists later confirmed that two of Mosander's discoveries were really new elements: cerium and lanthanum.
Mosander's didymium was not an element, however. In 1885, Auer found that didymium consisted of two simpler materials. The new elements were named neodymium and praseodymium. Auer chose the name neodymium because it means "new twin." Praseodymium, by comparison, means "green twin." Compounds of praseodymium are green.
Mosander, Auer, and other chemists of the time had only crude equipment with which to work. They never isolated any new element in a pure form. They found compounds of the element, usually a compound of the element and oxygen. The first pure samples of neodymium were not produced until 1925.
Neodymium is a soft, malleable metal. Malleable means capable of being hammered into thin sheets. It can be cut and shaped fairly easily. It has a melting point of 1,024°C (1,875°F) and a boiling point of about 3,030°C (5,490°F). Neodymium has a density of 7.0 grams per cubic centimeter.
Neodymium is somewhat reactive. For example, it combines with oxygen in the air to form a yellowish coating. To protect it from tarnishing, the metal is usually stored in mineral oil and wrapped in plastic.
Neodymium shows typical properties of an active metal. For example, it reacts with water and acids to release hydrogen gas.
Occurrence in nature
Neodymium is one of the most abundant of the rare earth elements. Its abundance in the Earth's crust is thought to be about 12 to 24 parts per million. That places it about 27th among the chemical elements. It is slightly less abundant than copper and zinc.
The most common ores of neodymium are monazite and bastnasite. These ores are the most common source for all the rare earth elements.
Predicting volcanic eruptions using neodymium
R are earth elements have very special applications in scientific research. For example, consider a discovery made by scientists at the Lawrence Berkeley Laboratory (LBL) Center for Isotope Geochemistry in Berkeley, California. These scientists were trying to predict the size of a volcanic eruption. If they knew an eruption was going to occur, could they estimate how much lava it would produce?
Surprisingly, they found the answer in isotopes of neodymium. They discovered that large volcanic eruptions produced lava with one kind of isotope composition. Smaller eruptions produced lava with a different isotope composition.
So when a volcano starts producing lava, it can be studied for neodymium isotopes. From the composition of isotopes, scientists may be able to predict how big the coming eruption will be. The LBL scientists hope to use this information to warn residents of the intensity of the eruption.
Neodymium combines with oxygen to form a yellowish coating. To protect it from tarnishing, the metal is usually stored in mineral oil and wrapped in plastic.
Seven naturally occurring isotopes of neodymium are known. These isotopes are neodymium-142, neodymium-143, neodymium-144, neodymium-145, neodymium-146, neodymium-148, and neodymium-150. Six of these isotopes are stable and one, neodymium-144, is radioactive. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope.
Seven radioactive isotopes of neodymium are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive. None of neodymium's radioactive isotopes has any important use.
Neodymium occurs with other rare earth elements in monazite, bastnasite, and allanite. It must first be separated from these
other elements. It is then obtained in a pure form by reacting neodymium fluoride (NdF3) with calcium:
Uses and compounds
Neodymium and its compounds have a number of important uses. One is in a kind of laser known as a neodymium yttrium aluminum garnet (Nd:YAG) laser. A laser is a device for producing very bright and focused light of a single color. The Nd:YAG laser is used for treating bronchial cancer and certain eye disorders. The bronchi are air tubes that Lead into the lungs.
Another important use of neodymium is in the manufacture of very strong magnets. The neodymium-iron-boron (NIB) magnet is one of the strongest magnets known. It is so strong it has to be handled with special care. Two NIB magnets can attract each other so strongly that they can smash into each other and shatter. An NIB magnet is inexpensive. An NIB magnet an inch in diameter and a quarter inch thick costs less than $10. Such magnets are used in stereo audio speakers.
Neodymium is also used in various optical (light) devices. For example, the General Electric Company makes a lightbulb called an "Enrich" bulb. The glass of the bulb contains a small amount of neodymium that filters out yellowish and greenish colors from the filament. The filament is the metal wire that is heated and gives off light. The light produced by the Enrich bulb is a very bright white light.
One of the oldest uses of neodymium is in coloring glass. The addition of a small amount of the element to glass gives it a greenish color. Some Tiffany lamp shades contain neodymium.
Two neodymium-iron-boron (NIB) magnets can attract each other so strongly that they can smash into each other and shatter.
Neodymium is regarded as moderately hazardous. Its compounds are known to irritate the eyes and skin. I t should be handled with caution.
Neodymium oxide was first isolated from a mixture of oxides called didymia. The element neodymium is the second most abundant lanthanide element in the igneous rocks of Earth's crust. Hydrated neodymium(III) salts are reddish and anhydrous neodymium compounds are blue. The compounds neodymium(III) chloride, bromide, iodide, nitrate, perchlorate, and acetate are very soluble; neodymium sulfate is somewhat soluble; the fluoride, hydroxide, oxide, carbonate, oxalate, and phosphate compounds are insoluble.
Neodymium is used to color special glasses, giving these glasses a blue-violet shade. It is also used to color television faceplates, to reduce the reflectivity of television screens. Nd2Fe14B magnets are among the most powerful. Neodymium compounds are used as laser materials, specifically as optically pulsed solid-state laser materials. One of the most important of these is Nd–YAG garnet (YAG = Y3Al5O12), which generates light having wavelengths of 1.06 micrometers (4.17 × 10−5 inches). This garnet laser has potential use in dental caries prevention. Finally, neodymium is used in the making of photographic filters (Nd2O3), magnets used in headphones, and ceramic capacitors.
see also Cerium; Dysprosium; Erbium; Europium; Gadolinium; Holmium; Lanthanum; Lutetium; Praseodymium; Promethium; Samarium; Terbium; Ytterbium.
Lea B. Zinner
American Chemical Society. Division of Chemical Education (2000) Chemistry Come Alive. Washington, DC: American Chemical Society.
Maestro, Patrick (1998). "From Properties to Industrial Applications." In Rare Earths, ed. R. S. Puche and P. Caro. Madrid: Editorial Complutense.
Weber, M. S. (1984). "Rare Earth Lasers." In Handbook on the Physics and Chemistry of Rare Earths, Vol. 4, ed. K. A. Gschneidner Jr. and L. R. Eyring. Amsterdam: North-Holland Physics Publishing.