erbium

Erbium (Er) is a chemical element with atomic number 68. It is a member of the lanthanide series, the group of rare earth elements. In nature, erbium occurs only in trace amounts within minerals such as xenotime and monazite, typically alongside other rare earths.

Erbium metal is soft, silvery-white, and relatively malleable, forming a protective oxide layer in air. Its most common oxidation state in compounds is +3; higher oxidation states are rare. It has properties typical of the lanthanides, including a tendency to form trivalent compounds and to be easily separated from other elements in ore processing.

Applications of erbium are dominated by optics and photonics. The leading commercial use is in optical fiber technology: doping glass with erbium ions enables amplification of light in the 1550-nanometer window via erbium-doped fiber amplifiers. Other important uses include Er:YAG solid-state lasers for medical and dental procedures, and phosphors for displays and lighting. Erbium compounds are also employed as neutron absorbers in some nuclear reactor designs.

Occurrence and production of erbium involve mining rare earth ores such as monazite and bastnasite, followed by chemical separation from other lanthanides using solvent extraction and ion-exchange techniques. The separation is challenging due to the chemical similarities among rare earth elements, requiring multiple purification steps.

History notes: erbium was identified in 1843 by Swedish chemist Carl Gustaf Mosander as a component of yttria. The name derives from Ytterby, the Swedish quarry village where the ore was first described.

Isotopes: naturally occurring erbium consists of several stable isotopes; many radioisotopes have been synthesized.

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