Erbium

Erbium was discovered in 1843. Its pink colored Er³⁺ ions have fluorescent properties useful in laser applications. It also show sharp absorption bands in near infrared, visible and ultraviolet light

History and Discovery

Erbium was discovered in 1843 by Carl Gustaf Mosander. He was working on metal oxide yttria which was derived from gadolinite. He found that metal contain two oxides including yttria and called them ‘’erbia’’ and ‘’terbia’’. Er₂O₃ was isolated in fairly pure form in 1905 by Georges Urbain and Charles James. It was not isolated in pure metallic form until 1935 when Wilhelm Klemm and Heinrich Bommer reduced its anhydrous chloride with potassium vapor [1]. Erbium was found in gadolinite mine Ytterby in Sweden from where it got its name.

Erbium

Periodic Table Classification	Group n/a Period 6
State at 20C	Solid
Color	Silvery white
Electron Configuration	[Xe] 4f12 6s2
Electron Number	68
Proton Number	68
Electron Shell	2, 8, 18, 30, 8, 2
Density	9.07 g.cm-3 at 20°C
Atomic number	68
Atomic Mass	167.26 g.mol -1
Electronegativity according to Pauling	1.24

Occurrence

Erbium is 45^th most abundant element in the Earth crust. Its concentration in earth is about 2.8 mg/kg and in sea water 0.9 ng/L. Like other lanthanide elements it is not found in free-state, it is bound in monazite sand ores. Earlier it was separated from ores through ion exchange chromatography method. The commercial source of erbium is xenotime (phosphate mineral), euxenite (brownish black mineral with metallic luster) and also in the clays of Southern China [2].

Physical Characteristics

In pure form it is malleable, soft and stable in air. It is not quickly oxidize as some other rare earth metals. Its salts color are rose colored. It has sharp absorption spectra bands in visible light. It is ferromagnetic below 19 K and antiferromagnetic between 19 and 80 K. Erbium is paramagnetic above 80 K [3]. Erbium sesquioxide (oxide containing three atoms of oxygen and two atoms of another element) are called erbia. Erbium has chemical symbol Er with atomic number 68. Its atomic weight is 167.259. Erbium melting point is 1592^OC and its boiling point is 2868^OC. It has high density at room temperature it is about 9.066 g/cm³.

Chemical Characteristics

Erbium tarnished in air slowly. It burns in air to form erbium (lll) oxide. Erbium is trivalent element.  It is also electropositive and react slowly with cold water and quickly with hot water and formed erbium hydroxide. It also react with all halogens and formed ErF₃ (pink), ErCl₃ (violet), ErBr₃ (violet) and ErI₃ (violet). Erbium is dissolves in dilute sulfuric acid to form hydrated Er (lll) ions [4].

Significance and Uses

• Erbium is used as photographic filter.
• It is useful as metallurgical additive due to its resilience.
• It is used in neutron absorbing control rod.
• Erbium lower hardness and improves workability when added to vanadium as alloy.
• In oxide form it is used as colorant for glass, cubic zirconia and porcelain.
• Erbium is doped in optical silica-glass fibers which are used in optical communication.
• Erbium nickel alloy is used in cryocoolers (standalone cooler).
• It is also useful in medical applications like dermatology and dentistry.
• Erbium has ability of adsorption of infrared light, so it is added in the glass of special safety spectacles for workers like welders and glass blowers.
• It is also used in some laser applications.

Health Effects

Erbium in the form of salts can stimulate metabolism. Its higher concentration is present in bones, in kidney and liver. It has no special biological role. Its compounds are not toxic but in dust form presents a fire and explosion hazards.

Isotopes of Erbium

Erbium naturally contain six stable isotopes:  ¹⁶²Er, ¹⁶⁴Er, ¹⁶⁶Er, ¹⁶⁷Er, ¹⁶⁸Er and ¹⁷⁰Er. It has twenty nine radioisotopes, ¹⁶⁹Er has half-life of 9.4 days. ¹⁷²Er has 49.3 hours, ¹⁶⁰Er has 28.58 hours, ¹⁶⁵Er has 10.36 hours and ¹⁷¹Er has 7.516 hours. All remaining have half-lives less than 3.5 hours and most of these have less than 4 minutes. The isotopes range in atomic weight from 142.9663 u to 176.9541 u.

REFERENCES

[1]. https://www.chemicool.com/elements/erbium.html

[2]. https://en.wikipedia.org/wiki/Erbium

[3]. Jackson, M. (2000). “Magnetism of Rare Earth”(PDF). The IRM quarterly. 10(3): 1.

[4]. “Chemical reactions of Erbium”. Webelements. Retrieved 2009-06-06