General information

Erbium is a chemical element with the element symbol Er and the atomic number 68. In the periodic table it is in the group of lanthanoids and is therefore also one of the rare earth metals. The name is derived from the Ytterby mine near Stockholm, as well as that of ytterbium, terbium and yttrium. Erbium (after Ytterby, a Swedish mine) was discovered by Carl Gustav Mosander in 1843. However, the supposedly pure oxide was a mixture of the oxides from erbium, scandium, holmium, thulium and ytterbium.

The chemists Marc Delafontaine and Berlin earned their earliest enlightenment. Pure erbium oxide was manufactured by 1905 French chemist Georges Urbain and American chemist Charles James.

Erbium is a rare metal (3,8 ppm).

Recovery

After a complex separation of the other Erbiumbegleiter the oxide is reacted with hydrogen fluoride to Erbiumfluorid. Subsequently, it is reduced to metallic erbium with calcium to form calcium fluoride. Separation of remaining calcium residues and impurities takes place in an additional remelting in vacuo.

Features

The silver-white, shiny metal of the rare earths is malleable, but also quite brittle. Erbium turns gray in air, but is then quite stable. At higher temperatures it burns to sesquioxide Er2O3. It reacts with water to form the hydroxide, producing hydrogen. It dissolves in mineral acids with the formation of hydrogen.

In its compounds it is present in the oxidation state + 3, the Er3 + cations form pink solutions in water. Solid salts are also colored pink.

Usage

Erbium-doped optical fibers are used for optical amplifiers capable of amplifying a light signal without first converting it into an electrical signal. Gold as the host material doped with a few hundred ppm of erbium is used as a sensor material magnetic calorimeter for high-resolution particle detection in physics and engineering.

Erbium is used in addition to other rare-earth elements such as neodymium or holmium for doping of laser crystals in solid state lasers (Er: YAG laser, see also Nd: YAG laser). The Er: YAG laser is mainly used in human medicine. It has a wavelength of 2940 nm and thus an extremely high absorption in the tissue water of about 12000 per cm. It comes to the sudden evaporation and thus the photoablation of tissue in thin layers. It is suitable for the removal of a variety of benign skin lesions. A biopsy is previously required to rule out malignancy. For example, ablated melanomas are strongly suspected of forming metastases through ablated cells via the bloodstream.

It is also used in the treatment of hard tissues such as bone, enamel and dentin (healthy and carious). Another erbium-based laser is the Er, Cr: YSGG laser, which has a slightly shorter wavelength of 2790 nm, but serves the same medical and / or dental indications.

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