- Erbium (Er) is a silvery-white, soft, and moderately stable rare earth metal with atomic number 68, belonging to the lanthanide series of the periodic table.
- Its electron configuration is [Xe] 4f¹² 6s², and it most commonly forms Er³⁺ ions as its stable oxidation state. The atomic structure consists of sixty-eight protons, typically ninety-nine or one hundred neutrons in its stable isotopes, and sixty-eight electrons arranged in six shells.
- Naturally occurring erbium is composed of six stable isotopes, with erbium-166 (¹⁶⁶Er) being the most abundant at about 33.5%.
- Erbium does not occur in elemental form in nature but is found in rare earth minerals such as xenotime (YPO₄), euxenite ((Y,Ca,Er,La,U,Th)(Nb,Ta,Ti)₂O₆), and monazite ((Ce,La,Nd,Th)PO₄). It is extracted and purified through solvent extraction and ion-exchange techniques, which separate it from other lanthanides. The primary production comes from China, though smaller amounts are also mined in countries like the USA, Brazil, Australia, and India.
- Erbium was discovered in 1843 by Swedish chemist Carl Gustaf Mosander, who separated it from yttrium and terbium in the mineral gadolinite. Its name is derived from the Swedish village of Ytterby, a historically important site for the discovery of several rare earth elements.
- Erbium is valued for its unique optical properties. Er³⁺ ions strongly absorb light in the infrared range, making erbium an essential dopant in fiber-optic communication systems, particularly in erbium-doped fiber amplifiers (EDFAs) that boost signal strength in long-distance telecommunication networks. Erbium is also used in lasers for medical applications, such as dermatology and dentistry, due to its ability to emit laser light at wavelengths strongly absorbed by water in biological tissues, enabling precise cutting with minimal thermal damage. In addition, erbium oxide (Er₂O₃) imparts a pink coloration to glass and ceramics, and erbium is used in some nuclear reactor control rods due to its neutron-absorbing properties.
- Chemically, erbium is relatively stable for a lanthanide. It tarnishes slowly in air, forming a protective oxide coating. Erbium reacts slowly with cold water and more readily with hot water to produce erbium hydroxide and hydrogen gas. It dissolves in most mineral acids, forming pale pink Er³⁺ salts.
- Biologically, erbium has no known essential role in living organisms. It is considered to have low to moderate toxicity, but fine powders and soluble compounds should be handled with care to avoid inhalation or ingestion.
- From an environmental perspective, erbium in its mineral form is stable and non-hazardous. However, the mining and refining processes for erbium, as with other rare earth elements, can produce significant chemical waste and potentially release radioactive materials from associated thorium- and uranium-bearing minerals.
