|Name, Symbol, Number||erbium, Er, 68|
|Group, Period, Block||n/a, 6, f|
|Appearance||silvery white |
|Atomic mass||167.259(3) g/mol|
|Electron configuration||[Xe] 4f12 6s2|
|Electrons per shell||2, 8, 18, 30, 8, 2|
|Density (near r.t.)||9.066 g/cm³|
|Liquid density at m.p.||8.86 g/cm³|
|Melting point||1802 K|
(1529 °C, 2784 °F)
|Boiling point||3141 K|
(2868 °C, 5194 °F)
|Heat of fusion||19.90 kJ/mol|
|Heat of vaporization||280 kJ/mol|
|Heat capacity||(25 °C) 28.12 J/(mol·K)|
|Electronegativity||1.24 (Pauling scale)|
|1st: 589.3 kJ/mol|
|2nd: 1150 kJ/mol|
|3rd: 2194 kJ/mol|
|Atomic radius||175 pm|
|Atomic radius (calc.)||226 pm|
|Magnetic ordering||no data|
|Electrical resistivity||(r.t.) (poly) 0.860 µΩ·m|
|Thermal conductivity||(300 K) 14.5 W/(m·K)|
|Thermal expansion||(r.t.) (poly)|
|Speed of sound (thin rod)||(20 °C) 2830 m/s|
|Speed of sound (thin rod)||(r.t.) 69.9 m/s|
|Shear modulus||28.3 GPa|
|Bulk modulus||44.4 GPa|
|Vickers hardness||589 MPa|
|Brinell hardness||814 MPa|
|CAS registry number||7440-52-0|
Like other rare earths, this element is never found as a free element in nature but is found bound in monazite sand ores. It has historically been very difficult and expensive to separate rare earths from each other in their ores but ion-exchange production techniques developed in the late twentieth century have greatly brought down the cost of production of all rare-earth metals and their chemical compounds. The principal commercial sources of erbium are from the minerals xenotime and euxenite.
Erbium (for Ytterby, a town in Sweden) was discovered by Carl Gustaf Mosander in 1843. Mosander separated "yttria" from the mineral gadolinite into three fractions which he called yttria, erbia, and terbia. He named the new element after the town of Ytterby where large concentrations of yttria and erbium are located. Erbia and terbia, however, were confused at this time. After 1860, terbia was renamed erbia and after 1877 what had been known as erbia was renamed terbia. Fairly pure Er2O3 was independently isolated in 1905 by Georges Urbain and Charles James. Reasonably pure metal wasn't produced until 1934 when workers reduced the anhydrous chloride with potassium vapor.
Erbium is an inner transition metal (or lanthanide) that lies in period six of the periodic table, between holmium and thulium. A trivalent element, pure erbium metal is malleable (or easily shaped), soft yet stable in air, and does not oxidize as quickly as some other rare earth metals.
Salts of erbium are rose-colored and the element gives a characteristic sharp absorption spectra in visible light, ultraviolet, and near infrared. Otherwise it looks much like the other rare earths. Its sesquioxide is called erbia. Erbium's properties are to a degree dictated by the kind and amount of impurities present.
Erbium doped glasses or crystals can be used as optical amplification media, where erbium ions are optically pumped at around 980nm or 1480nm and then radiate light at 1550nm. This process can be used to create lasers and optical amplifiers. The 1550nm wavelength is especially important for optical communications because standard single mode optical fibers have minimal loss at this particular wavelength.
Naturally occurring erbium is composed of six stable isotopes—Er-162, Er-164, Er-166, Er-167, Er-168, Er-170—with Er-166 being the most abundant (33.6 percent natural abundance). 23 radioisotopes have been characterized, with the most stable being Er-169 with a half life of 9.4 days, Er-172 with a half-life of 49.3 hours, Er-160 with a half-life of 28.58 hours, Er-165 with a half-life of 10.36 hours, and Er-171 with a half life of 7.516 hours. All of the remaining radioactive isotopes have half-lives that are less than 3.5 hours, and the majority of these have half lives that are less than four minutes. This element also has six meta states, with the most stable being Er-167m (t½ 2.269 seconds).
The isotopes of erbium range in atomic weight from 144.957 amu (Er-145) to 173.944 amu (Er-174). The primary decay mode before the most abundant stable isotope, Er-166, is electron capture, and the primary mode after is beta decay. The primary decay products before Er-166 are element 67 (holmium) isotopes, and the primary products after are element 69 (thulium) isotopes.
Erbium's everyday uses are varied. It is commonly used as a photographic filter and because of its resilience it is useful as a metallurgical additive. Other uses:
- Used in nuclear technology as a neutron absorber.
- Used as a dopant in fiber optic laser amplifiers.
- When added to vanadium as an alloy erbium lowers hardness and improves workability.
- Erbium oxide has a pink color and is sometimes used as a colorant for glass and porcelain. The glass is then often used in sunglasses and cheap jewelry.
- Erbium doped optical silica-glass fibers is the active element in erbium-doped fiber amplifiers (EDFAs) which are widely used in optical communications. The same fibers can be used to create fiber lasers. Co-doping of optical fiber with Er and Yb is used in high power Er/Yb fiber lasers, which gradually replace CO2 lasers for metal welding and cutting applications. Erbium can also be used in erbium-doped waveguide amplifiers.
Biological role and precautions
Erbium does not play any known biological role but is thought by some to be able to stimulate metabolism. As with the other lanthanides, erbium compounds have low-to-moderate toxicity, but their toxicity has not been investigated in detail. Metallic erbium in dust form presents a fire and explosion hazard.
- The term "rare earth metals" (or "rare earth elements") is a trivial name applied to 16 chemical elements: scandium, yttrium, and 14 of the 15 lanthanides (excluding promethium), which occur naturally on Earth. Some definitions also include the actinides. The word "earth" is an obsolete term for oxide. The term "rare earth" is discouraged by the International Union of Pure and Applied Chemistry (IUPAC), as these elements are relatively abundant in the Earth's crust.
- Chang, Raymond. 2006. Chemistry. 9th ed. New York: McGraw-Hill Science/Engineering/Math. ISBN 0073221031
- Cotton, F. Albert, and Geoffrey Wilkinson. 1980. Advanced Inorganic Chemistry. 4th ed. New York: Wiley. ISBN 0-471-02775-8
- "Erbium" Los Alamos National Laboratory, Chemistry Division. Retrieved January 4, 2008.
- "Erbium" It's Elemental. Jefferson Lab. Retrieved January 4, 2008.
- Greenwood, N.N. and A. Earnshaw. 1998. Chemistry of the Elements. 2nd ed. Oxford, U.K.; Burlington, MA: Butterworth-Heinemann, Elsevier Science. ISBN 0750633654 Online version Retrieved January 4, 2008.
- Jones, Adrian P., Frances Wall, and C. Terry Williams, eds. 1996. Rare Earth Minerals: Chemistry, Origin and Ore Deposits. The Mineralogical Society Series. London, UK: Chapman and Hall. ISBN 0412610302
- Stwertka, Albert. 1998. Guide to the Elements. Rev. ed. Oxford, UK: Oxford University Press. ISBN 0-19-508083-1
All links retrieved August 18, 2017.
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