Erbium is a bright silvery metal, which is soft and malleable. It is a member of the lanthanoid group of the Periodic Table and the 44th most abundant element within the Earth’s crust. Erbium reacts slowly with air and water and dissolves in acids. Despite this, in comparison with the other rare earth metals, it is quite corrosion resistant.
Erbium was discovered in 1843 by Carl Gustaf Mosander. Whilst analysing the mineral yttria, which is ytterbium oxide, Mosander concluded that this oxide may contain other elements which had not yet been found. He had suspected this as a few years previously he had extracted the element lanthanum from a sample of cerium oxide. Mosander turned out to be correct, and from yttria he was able to extract two new oxides, terbium oxide and erbium oxide. He then named these elements after the Swedish town, Ytterby, after which the mineral yttria was named, and where it is often found.
Erbium, like all other rare earth elements, is mainly obtained from the Inner Mongolian mines within China. It is found in the rare earth ores monazite and bastnasite, although it is not a major component of either, but is present in amounts worthy of extraction. Other minerals containing erbium include xenotime (yttrium phosphate) and euxerite (a complex ore of many metals), and these are, in fact, better sources for erbium. World production of the metal is mainly in the form of erbium oxide. Forecast estimates for 2014 predict the market to have 241 mt surplus, with 940 mt of demand outweighed by a 1,181 mt supply.
Erbium has two main commercial applications, as a medical laser and in fibre optic cables. Erbium lasers have medical and dental uses because they are suited to energy delivery without thermal build up in human tissue. In cosmetic treatments, they are used to ablate the epidermis, revealing the smoother and younger-looking underlying skin. In dentistry, erbium lasers have been proven safe and effective for the removal of tooth decay and cavity preparation. The other main use of erbium is in transmitting data through fibre optics. Fibre optic cables contain periodically-spaced lengths of erbium-doped fibre which acts as a laser amplifier. Other uses for erbium include colouring glass pink, use in nuclear applications and use in vanadium alloys.
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