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Lanthanum [ lanta ː n] is a chemical element with the element symbol La and atomic number 57 It belongs to the transition metals and the metals of the rare earths in the periodic table it is in the 6th period and the third sub-group (group 3) or scandium. Usually it is also numbered among the lanthanides, even if the f- shell of the element is empty.

  • 5.1 As alloy
  • 5.2 As lanthanum
  • 5.3 As lanthanum carbonate


Lanthanum (Greek λανθάνειν, " be hidden " lanthanein, ) was discovered in 1839 by Swedish chemist and surgeon Carl Gustav Mosander. For a supposedly pure cerium he won by fractional crystallization of lanthanum.


Lanthanum is of course only in chemical compounds associated with other lanthanides in various minerals ago. Mainly, these are:

  • Monazite ( (Ce, La, Th, Nd, Y) PO4 )
  • Bastnäsit ( (Ce, La, Y) CO3F )

Production and representation

After an extensive separation of the other Lanthanbegleiter the oxide is reacted with hydrogen fluoride to lanthanum. This is then reduced with calcium to form calcium fluoride to lanthanum. The removal of residual calcium residues and contaminants carried in an additional remelting in a vacuum.


Physical Properties

The silver- white shiny metal is ductile and malleable ( ductile). There are three metallic modifications.

Chemical Properties

Lanthanum is ignoble. It coats on the air quickly with a white oxide, which further reacts in moist air to the hydroxide.

At temperatures above 440 ° C burns lanthanum to lanthanum oxide ( La2O3 ). The formation of hydrogen takes place in cold water a slow, warm water for a rapid response to the hydroxide.

In dilute acids Lanthanum dissolves with evolution of hydrogen.

With many items it reacts directly in the heat, with halogens at room temperature. Lanthanum and hydrogen form a black, water-sensitive unstöchiometrisches hydride.


Lanthanum ingredient is mixed metal. Pyrophoric materials for flints contain 25 to 45 weight percent lanthanum. In addition, it is used as a reducing agent in metallurgy. A cast iron addition it aids in the formation of spheroidal graphite, as an alloying element is effective for improving the oxidation resistance. Lanthanbeimengungen reduce the hardness and temperature sensitivity of molybdenum.

High-quality cathode for generating free electrons consist of lanthanum hexaboride as a replacement for tungsten filament. High-purity lanthanum oxide is used in the glass industry for the production of high-quality glass with a high refractive index for the optical system such as a camera lens.

As alloying

Lanthanum cobalt alloy is used as LaCo5 magnetic material, lanthanum-doped barium titanate, for the production of PTC thermistors (temperature dependent resistors ) are used. In combination with cobalt, iron, manganese, strontium, and it serves as a cathode for the high-temperature fuel cells ( SOFC). " Contaminated " lanthanum - nickel ( LaNi5 ) is used as a hydrogen storage in nickel -metal hydride batteries using. In addition, it comes in carbon arc lamps for studio lighting and in Filmvorführanlagen (historical application? ) Before.

  • With titanium:

A metal alloy with material compositions of lanthanum and titanium is attributed to the effect that in cutting visual processing, the chip length is reduced. This should be facilitated processing metal.

In the medical field corrosion resistant and easy to sterilize instruments are made from the alloy metal. Said metal alloy having a titanium to be particularly well suited for tools and devices for surgical procedures, since the allergy tilt when using such metal alloy having a titanium in relation to the other alloys to be low.

As lanthanum

  • Production of glasses ( lanthanum ) with a comparatively high refractive index, which in turn only slightly with the wavelength change (low dispersion), for cameras, telescope lenses, and eyeglass
  • Production of crystal glass and porcelain glazes. It will replace more toxic lead compounds while improving the chemical resistance (improvement of alkali resistance, " dishwasher safe " )
  • Addition of catalyst to the zeolite during fluid catalytic cracking in the refinery for petroleum processing
  • Production of ceramic capacitor masses and silicate-free glasses
  • Component of glass polishing agents
  • Manufacture of thermionic cathodes for electron tubes (also Lanthanboride )

As lanthanum carbonate

  • Medication to lower phosphate levels in dialysis patients (so-called phosphate binders )


Lanthanum is classified as a low toxicity. A toxic dose is unknown. However, lanthanum powder is considered highly corrosive because it is very easy by example Skin moisture to basic lanthanum hydroxide reacts ( similar to the elements calcium and strontium ). The lethal dose is 720 mg in rats.


In compounds of lanthanum exists as colorless La3 .

  • Lanthanum oxide La2O3
  • Lanthanum LaF3
  • Lanthanum chloride LaCl3
  • Lanthanbromid LaBr3
  • Lanthaniodid LaI3
  • Lanthanum nitrate La ( NO3) 3
  • Lanthanum La2 (SO4) 3
  • Lanthanum
  • Lanthanum hexaboride