rare-earth metals


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rare-earth metals,

in chemistry, group of metals including those of the lanthanide serieslanthanide series,
a series of metallic elements, included in the rare-earth metals, in Group 3 of the periodic table. Members of the series are often called lanthanides, although lanthanum (atomic number 57) is not always considered a member of the series.
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 and actinide seriesactinide series,
a series of radioactive metallic elements in Group 3 of the periodic table. Members of the series are often called actinides, although actinium (at. no. 89) is not always considered a member of the series.
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 and usually yttriumyttrium
[for Ytterby, a town in Sweden], metallic chemical element; symbol Y; at. no. 39; at. wt. 88.90585; m.p. about 1,522°C;; b.p. 3,338°C;; sp. gr. about 4.45; valence +3. Yttrium is a highly crystalline iron-gray metal.
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, sometimes scandiumscandium
, metallic chemical element; symbol Sc; at. no. 21; at. wt. 44.95591; m.p. 1,541°C;; b.p. 2,831°C;; sp. gr. 2.99 at 20°C;; valence +3. Scandium is a soft silver-white metal.
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 and thoriumthorium
[from Thor], radioactive chemical element; symbol Th; at. no. 90; mass number of most stable isotope 232; m.p. about 1,750°C;; b.p. about 4,790°C;; sp. gr. 11.7 at 20°C;; valence +4.

Thorium is a soft, ductile, lustrous, silver-white, radioactive metal.
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, and rarely zirconiumzirconium
, metallic chemical element; symbol Zr; at. no. 40; at. wt. 91.224; m.p. about 1,852°C;; b.p. 4,377°C;; sp. gr. 6.5 at 20°C;; valence +2, +3, or +4.

Zirconium is a very strong, malleable, ductile, lustrous silver-gray metal.
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. Promethium, which is not found in nature, is not usually considered a rare-earth metal. The metals usually occur together in minerals as their oxides (rare earthsrare earths,
in chemistry, oxides of the rare-earth metals. They were once thought to be elements themselves. They are widely distributed in the earth's crust and are fairly abundant, although they were once thought to be very scarce.
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) and are somewhat difficult to separate because of their chemical similarity. A subgroup of the rare-earth metals, consisting of those with atomic numbers between 57 and 63 and ytterbium, is often called the cerium metals. Misch metal is an alloy of the cerium metals often used in lighter flints, in alloys with other metals (especially magnesiummagnesium
, metallic chemical element; symbol Mg; at. no. 12; at. wt. 24.3050; m.p. about 648.8°C;; b.p. about 1,090°C;; sp. gr. 1.738 at 20°C;; valence +2. In 1808, Sir Humphry Davy discovered magnesium in its oxide, although it is not certain that he isolated the
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), and to remove residual gases in the manufacture of vacuum tubes. Individual metals may be isolated as their compounds by ion exchange methods, solvent extraction, or fractional crystallization, and chemically or electrolytically reduced to the pure metal. Uses are discussed in articles on individual elements.

Bibliography

See F. H. Spedding and A. H. Daane, ed., The Rare Earths (1961, repr. 1971); E. C. Subbarao and W. E. Wallace, ed., Science and Technology of Rare Earth Metals (1980).

References in periodicals archive ?
The company is engaged in development and production of rare-earth metals in Africa.
has developed a new electric motor for hybrid vehicles that tackles two top challenges in manufacturing the crucial drivetrain component: The high cost and uncertain supply of the rare-earth metals used in their powerful magnets.
International spot prices for rare-earth metals are rising amid moves by China to stockpile those key materials for high-tech consumer electronics and hybrid vehicles.
After their meeting, the Presidents attended a ceremony of signing the documents related to supply of oil and petroleum products, the use of subsoil resources at the Kharasan-1, Akdala and South Inkai fields, and cooperation in alternative energy and rare and rare-earth metals mining, the Kremlin press service said.
com, India's premier research company in export import statistics, announced today that India's Inorganic Chemicals, Organic or Inorganic Compounds of Precious Metals of Rare-Earth Metals and Radioactive Elements of Isotopes imports in March- 2014 has fallen to US$ 336.
said Tuesday it has developed what it describes as the world's first process to extract and recycle rare-earth metals from the nickel hydride batteries of its used hybrid cars on a mass-production basis.
Summary: WASHINGTON/BEIJING - The United States, Europe and Japan have joined forces to challenge China's restrictions on exports of rare-earth metals, escalating a trade row over access to some of the most important raw materials used in advanced technologies.
International Resource News-February 7, 2011--China stocking up in rare-earth metals sector(C)1994-2011 ENPublishing - http://www.
stocks of rare-earth metals and find new ways to collect, use, reduce, reuse, and recycle these metals.
That may change, however, as demand for rare-earth metals rises for use in products such as smartphones, electric and hybrid cars, common computer monitors and televisions.
Based on its composition, the LBL team's TMSM boasts a 22-42% gain in energy savings performance over other low emissivity glazings and a significant decrease in cost compared to similar mirrors constructed with rare-earth metals.
California -- Eight citizen and conservation groups, including NPCA, recently opposed a proposal in San Bernardino County to expand a rare-earth metals mine at Mountain Pass, California, in large part because the company that will do the work has a long history of polluting the region's air, land, and water.