Carl Gustaf Mosander, a Swedish chemist, discovered lanthanum in 1839. Lanthanum is named from lanthano, the Greek word meaning "to be hidden".
Lanthanum is a silvery metal, malleable, ductile, and soft enough to be cut by a knife. It is the first element in the Periodic Table to exhibit "lanthanide contraction", a property that is displayed by all of the lanthanide elements, save for the rare earths yttrium and scandium. It is one of the most reactive of the rare-earth metals and reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulphur, and with halogens. It oxidizes rapidly when exposed to air.
Lanthanum is obtained through the process of solvent extraction of light rare earth minerals such as bastnaesite and most of it comes from China. Some is produced in the United States from stockpiled ores, and some is produced in India.
APPLICATIONS OF LANTHANUM
Glass and Ceramics: Lanthanum oxide (La2O3) improves the alkali resistance of glass, and is used in making special optical glasses, such as infrared absorbing glass. Lanthanum is also used as doping agents in camera and telescope lenses because of its high refractive index and low dispersion indices. Lanthanum oxide is also used for polishing glass and gemstones.
Energy and Batteries: Lanthanum is an intermetallic component of Nickel Metal Hydride (NiMH) batteries which are used by several electric automobile producers, are used in laptop computers, and other hand-held electronic devices. Lanthanum is also used in hydrogen storage fuel cell materials for stationary and automotive where they can store up to 400 times their own volume of hydrogen gas in a reversible adsorption process.
Alloys: Lanthanum is one of the alloying elements used in High Strength Low Alloy (HSLA) steels for automobiles and cold weather applications such as pipelines. Small amounts of lanthanum added to steel improve its malleability, resistance to impact and ductility. Added to iron, lanthanum helps to produce nodular cast iron for automotive rear ends, transmissions and transfer cases.Lanthanum added to molybdenum decreases the hardness of this metal and its sensitivity to temperature variations. It is also a component of Mischmetal, a pyrophoric alloy used in such things as lighter flints or strikers, and in carbon lighting applications used especially by the motion picture industry.
Medicine: Lanthanum carbonate is used as a phosphate binder for the treatment of hyperphosphatemia.
Other uses: A major end use of lanthanum is in petroleum cracking and chemical industry catalysts. Small amounts of lanthanum are present in many pool products to remove the phosphates that feed algae. Lanthanum oxide and the boride (LaB6) are used in electronic vacuum tubes as hot cathode materials with strong emissivity of electrons and crystals of LaB6 are used in high brightness, extended life, thermionic electron emitters for scanning electron microscopes.
LINKS: For chemical and physical properties: www.webelements.com or http://education.jlab.org/itselemental/ele057.html
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