Erbium compounds are compounds containing the element

erbium Erbium is a chemical element with the symbol Er and atomic number 68. A silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare-earth element ...

(Er). These compounds are usually dominated by erbium in the +3 oxidation state, although the +2, +1 and 0Yttrium and all lanthanides except Ce and Pm have been observed in the oxidation state 0 in bis(1,3,5-tri-t-butylbenzene) complexes, see and

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

s have also been reported.

Oxides

Erbium(III) oxide Erbium(III) oxide is the inorganic compound with the formula . It is a pink paramagnetic solid. It finds uses in various optical materials. Structure Erbium(III) oxide has a cubic structure resembling the bixbyite motif. The Er3+ centers are oc ...

(also known as erbia) is the only known oxide of erbium, first isolated by

Carl Gustaf Mosander Carl Gustaf Mosander (10 September 1797 – 15 October 1858) was a Swedish chemist. He discovered the rare earth elements lanthanum, erbium and terbium. Early life and education Born in Kalmar, Mosander attended school there until he moved t ...

in 1843, and first obtained in pure form in 1905 by

Georges Urbain Georges Urbain (12 April 1872 – 5 November 1938) was a French chemist, a professor of the Sorbonne, a member of the Institut de France, and director of the Institute of Chemistry in Paris. Much of his work focused on the rare earths, isolating and ...

and

Charles James Charles James may refer to: * Charles James (British Army officer) (1757/8–1821), English army officer and writer * Charles James (attorney) (born 1954), former U.S. assistant attorney general * Charles James (American football) (born 1990), Amer ...

. It has a cubic structure resembling the

bixbyite Bixbyite is a manganese iron oxide mineral with chemical formula: (Mn,Fe)2O3. The iron/manganese ratio is quite variable and many specimens have almost no iron. It is a metallic dark black with a Mohs hardness of 6.0 - 6.5. It is a somewhat rare ...

motif. The Er³⁺ centers are octahedral. The formation of erbium oxide is accomplished by burning erbium metal. Erbium oxide is insoluble in water and soluble in mineral acids.

Halides

Erbium(III) fluoride is a pinkish powder that can be produced by reacting erbium(III) nitrate and

ammonium fluoride Ammonium fluoride is the inorganic compound with the formula NH4F. It crystallizes as small colourless prisms, having a sharp saline taste, and is highly soluble in water. Like all fluoride salts, it is moderately toxic in both acute and chronic o ...

. It can be used to make infrared light-transmitting materials and up-converting luminescent materials.

Erbium(III) chloride Erbium(III) chloride is a violet solid with the formula . It is used in the preparation of erbium metal. Preparation Anhydrous erbium(III) chloride can be produced by the ammonium chloride route. In the first step, erbium(III) oxide is heated ...

is a violet compounds that can be formed by first heating erbium(III) oxide and ammonium chloride to prouce the

ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary a ...

salt of the pentachloride ( H₄sub>2ErCl₅) then heating it in a vacuum at 350-400 ºC. It forms crystals of the type, with

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

crystals and the

point group In geometry, a point group is a mathematical group of symmetry operations (isometries in a Euclidean space) that have a fixed point in common. The coordinate origin of the Euclidean space is conventionally taken to be a fixed point, and every p ...

''C''2/m.Erbium(III) chloride hexahydrate also forms monoclinic crystals with the point group of ''P''2/''n'' (''P''2/''c'') - ''C''⁴_2h. In this compound, erbium is octa-coordinated to form ions with the isolated completing the structure. Erbium(III) bromide is a violet solid. It is used, like other metal bromide compounds, in water treatment, chemical analysis and for certain crystal growth applications. Erbium(III) iodide is a slightly pink compound that is insoluble in water. It can be prepared by directly reacting erbium with

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

Borides

Erbium tetraboride is a

boride A boride is a compound between boron and a less electronegative element, for example silicon boride (SiB3 and SiB6). The borides are a very large group of compounds that are generally high melting and are covalent more than ionic in nature. Some bor ...

of erbium. It is hard and has a high melting point. It can be used in

semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

s, the

blades A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are to be used on. Historic ...

gas turbines A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...

, and the

nozzles A nozzle is a device designed to control the direction or characteristics of a fluid flow (specially to increase velocity) as it exits (or enters) an enclosed chamber or pipe. A nozzle is often a pipe or tube of varying cross sectional area, a ...

of rocket engines. Erbium hexaboride is another boride of erbium, with a

calcium hexaboride Calcium hexaboride (sometimes calcium boride) is a compound of calcium and boron with the chemical formula CaB6. It is an important material due to its high electrical conductivity, hardness, chemical stability, and melting point. It is a black, ...

structure. It is

isostructural Isostructural chemical compounds have similar chemical structures. "Isomorphous" when used in the relation to crystal structures is not synonymous: in addition to the same atomic connectivity that characterises isostructural compounds, isomorphous s ...

with all other rare-earth hexaboride compounds including lanthanum hexaboride, samarium hexaboride, and cerium hexaboride.

Other compounds

Erbium(III) hydroxide Erbium(III) hydroxide is an inorganic compound with chemical formula Er(OH)3. Chemical properties Erbium(III) hydroxide reacts with acids In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of ...

is a pink solid that decomposes to ErO(OH) at an elevated temperature, then further heating will produce erbium(III) oxide. Erbium(III) phosphide (ErP) is also a pink solid that can be formed by the direct reaction of its constituent elements. It forms crystals of a cubic system,

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...

''Fm''3''m''. Erbium(III) nitrate (Er(NO₃)₃) forms pink crystals. It is readily soluble in water and forms crystalline hydrates. Erbium(III) acetate is a light pink solid that is used to synthesize some optical materials. The tetrahydrate of erbium(III) acetate is thermally decomposed at 90 °C, giving a proposed anhydride: : Er(CH₃COO)₃·4H₂O → Er(CH₃COO)₃ + 4 H₂O Continuing heating to 310 °C will form

ketene In organic chemistry, a ketene is an organic compound of the form , where R and R' are two arbitrary monovalent chemical groups (or two separate substitution sites in the same molecule). The name may also refer to the specific compound etheno ...

: : Er(CH₃COO)₃ → Er(OH)(CH₃COO)₂ + CH₂=C=O At 350 °C, the proposed Er(OH)(CH₃COO)₂ loses

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...

to yield a material of the formula ErOCH₃COO, forming Er₂O₂CO₃ at 390 °C, finally obtaining Er₂O₃ at 590 °C.

Organoerbium compounds

Organoerbium compounds are very similar to those of the other lanthanides, as they all share an inability to undergo

π backbonding In chemistry, π backbonding, also called π backdonation, is when electrons move from an atomic orbital on one atom to an appropriate symmetry antibonding orbital on a ''π-acceptor ligand''. It is especially common in the organometallic che ...

. They are thus mostly restricted to the mostly ionic

cyclopentadienide In chemistry, the cyclopentadienyl anion or cyclopentadienide is an aromatic species with a formula of and abbreviated as Cp−. It is formed from the deprotonation of the molecule cyclopentadiene. Properties The cyclopentadienyl anion ...

s (isostructural with those of lanthanum) and the σ-bonded simple alkyls and aryls, some of which may be polymeric.Greenwood and Earnshaw, pp. 1248–9

References