Lanthanum is a chemical element, with the symbol La and the atomic number 57.
Lanthanum gave its name to the family of lanthanides which are part of the rare
earths. Its name derives from the Greek word "lanthanum", which means "to hide":
lanthanum has long been hidden in cerium oxide.
At room temperature lanthanum is a silver gray, malleable, ductile metal, soft
enough to be cut with a knife. It oxidizes in air and in water.
Lighter stone: made from mischmetal, a mixture of rare earths, containing about
55% of cerium, 20% of lanthanum, 15% of neodymium, 5% of praseodymium, 1% of
samarium and yttrium
Storage of hydrogen: the LaNi5 alloy in the form of foam, absorbs 400 times its
own volume.
Catalyst for petrol engines: LaPbMnO3 applied to lanthanum oxide is a good
catalyst, more economical than the platinum and palladium currently used.
Optical glass: the addition of lanthanum compounds, La2O3 oxide or La2 carbonate
(CO3) 3, increases the refractive index and decreases the chromatic aberration
Other uses. Like other rare earths, it is used for magnetic alloys, in
superconductive compounds, as a component of phosphors in cathode ray tubes, as
a "dopant" in crystals for lasers, as a fluorescent compound (lanthanum
phosphate LaPO4) studied for anti-fraud markings.
Combined with tungsten, it is used in the form of cylindrical rods as an
emissive electrode for TiG welding torches or plasma welding torches. The
tungsten - lanthanum oxide alloy makes it possible to increase the admissible
intensity, to facilitate the ignition of the arc and to limit as much as
possible the degradation of the electrode during welding.
Lanthanum carbonate La2 (CO3) 3 ingested in the form of chewable tablets is used
as a phosphate binder to control hyperphosphatemia in hemodialysis patients to
prevent renal osteodystrophy (source: Fosrenol, Shire monograph).
Hot cathode: lanthanum hexaboride is used in certain hot cathodes.
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rhenium germanium zirconium cadmium hafnium
barium lithium beryllium strontium calcium
Tantalum gadolinium samarium yttrium ytterbium
Lutetium praseodymium holmium erbium thulium dysprosium
terbium europium lanthanum cerium neodymium scandium
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