Scandium oxide

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Scandium(III) oxide
Kristallstruktur Lanthanoid-C-Typ.png
__ Sc 3+__ O 2−
Names
IUPAC name
Scandium(III) oxide
Other names
Scandia, scandium sesquioxide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.031.844 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/3O.2Sc
  • O=[Sc]O[Sc]=O
Properties
Sc2O3
Molar mass 137.910 g/mol
AppearanceWhite powder
Density 3.86 g/cm3
Melting point 2,485 °C (4,505 °F; 2,758 K)
insoluble in water
Solubility soluble in hot acids (reacts)
Structure [1]
Bixbyite
Ia3 (No. 206)
a = 985 pm
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
0
0
Related compounds
Other anions
Scandium(III) sulfide
Other cations
Yttrium(III) oxide
Lutetium(III) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Scandium(III) oxide or scandia is a inorganic compound with formula Sc 2 O 3. It is one of several oxides of rare earth elements with a high melting point. It is used in the preparation of other scandium compounds as well as in high-temperature systems (for its resistance to heat and thermal shock), electronic ceramics, and glass composition (as a helper material).

Contents

Structure and physical properties

Scandium(III) oxide adopts a cubic crystal structure (point group: tetrahedral (Th), space group: Ia3) containing 6-coordinate metal centres. [2] Powder diffraction analysis shows ScO bond distances of 2.1592.071 Å. [1]

Scandium oxide is an insulator with a band gap of 6.0 eV. [3]

Production

Scandium oxide is the primary form of refined scandium produced by the mining industry. Scandium-rich ores, such as thortveitite (Sc,Y)2(Si2O7) and kolbeckite ScPO4·2H2O are rare, however trace amounts of scandium are present in many other minerals. Scandium oxide is therefore predominantly produced as a by-product from the extraction of other elements.

Reactions

Scandium oxide is the primary form of refined scandium produced by the mining industry, making it the start point for all scandium chemistry.

Scandium oxide reacts with most acids upon heating, to produce the expected hydrated product. For example, heating in excess aqueous HCl produces hydrated ScCl3·nH2O. This can be rendered anhydrous by evaporation to dryness in the presence of NH4Cl, with the mixture then being purified by removal of NH4Cl by sublimation at 300-500 °C. [4] The presence of NH4Cl is required, as the hydrated ScCl3·nH2O would otherwise form a mixed oxychloride upon drying.

Sc2O3 + 6 HCl + x H2O → 2 ScCl3·nH2O + 3 H2O
ScCl3·nH2O + n NH4Cl → ScCl3 + n H2O + n NH4Cl

Likewise, it is converted into hydrated scandium(III) triflate (Sc(OTf)3·nH2O) by a reaction with triflic acid. [5]

Metallic scandium is produced industrially by the reduction of scandium oxide; this proceeds via conversion to scandium fluoride followed by a reduction with metallic calcium. This process is in some ways similar to the Kroll process for the production of metallic titanium.

Scandium oxide forms scandate salts with alkalis, unlike its higher homologues yttrium oxide and lanthanum oxide (but like lutetium oxide), for example forming K3Sc(OH)6 with KOH. In this, scandium oxide shows more similarity with aluminium oxide.

Natural occurrence

Natural scandia, although impure, occurs as mineral kangite. [6]

Related Research Articles

Iron(III) chloride describes the inorganic compounds with the formula FeCl3(H2O)x. Also called ferric chloride, these compounds are some of the most important and commonplace compounds of iron. They are available both in anhydrous and in hydrated forms which are both hygroscopic. They feature iron in its +3 oxidation state. The anhydrous derivative is a Lewis acid, while all forms are mild oxidizing agents. It is used as a water cleaner and as an etchant for metals.

<span class="mw-page-title-main">Cerium(III) chloride</span> Chemical compound

Cerium(III) chloride (CeCl3), also known as cerous chloride or cerium trichloride, is a compound of cerium and chlorine. It is a white hygroscopic salt; it rapidly absorbs water on exposure to moist air to form a hydrate, which appears to be of variable composition, though the heptahydrate CeCl3·7H2O is known. It is highly soluble in water, and (when anhydrous) it is soluble in ethanol and acetone.

<span class="mw-page-title-main">Praseodymium(III) chloride</span> Chemical compound

Praseodymium(III) chloride is the inorganic compound with the formula PrCl3. Like other lanthanide trichlorides, it exists both in the anhydrous and hydrated forms. It is a blue-green solid that rapidly absorbs water on exposure to moist air to form a light green heptahydrate.

Neodymium(III) chloride or neodymium trichloride is a chemical compound of neodymium and chlorine with the formula NdCl3. This anhydrous compound is a mauve-colored solid that rapidly absorbs water on exposure to air to form a purple-colored hexahydrate, NdCl3·6H2O. Neodymium(III) chloride is produced from minerals monazite and bastnäsite using a complex multistage extraction process. The chloride has several important applications as an intermediate chemical for production of neodymium metal and neodymium-based lasers and optical fibers. Other applications include a catalyst in organic synthesis and in decomposition of waste water contamination, corrosion protection of aluminium and its alloys, and fluorescent labeling of organic molecules (DNA).

<span class="mw-page-title-main">Samarium(III) chloride</span> Chemical compound

Samarium(III) chloride, also known as samarium trichloride, is an inorganic compound of samarium and chloride. It is a pale yellow salt that rapidly absorbs water to form a hexahydrate, SmCl3.6H2O. The compound has few practical applications but is used in laboratories for research on new compounds of samarium.

<span class="mw-page-title-main">Europium(III) chloride</span> Chemical compound

Europium(III) chloride is an inorganic compound with the formula EuCl3. The anhydrous compound is a yellow solid. Being hygroscopic it rapidly absorbs water to form a white crystalline hexahydrate, EuCl3·6H2O, which is colourless. The compound is used in research.

<span class="mw-page-title-main">Aluminium chloride</span> Chemical compound

Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms a hexahydrate with the formula [Al(H2O)6]Cl3, containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are colourless crystals, but samples are often contaminated with iron(III) chloride, giving them a yellow colour.

<span class="mw-page-title-main">Dysprosium(III) chloride</span> Chemical compound

Dysprosium(III) chloride (DyCl3), also known as dysprosium trichloride, is a compound of dysprosium and chlorine. It is a white to yellow solid which rapidly absorbs water on exposure to moist air to form a hexahydrate, DyCl3·6H2O. Simple rapid heating of the hydrate causes partial hydrolysis to an oxychloride, DyOCl.

<span class="mw-page-title-main">Chromium(III) chloride</span> Chemical compound

Chromium(III) chloride (also called chromic chloride) is an inorganic chemical compound with the chemical formula CrCl3. It forms several hydrates with the formula CrCl3·nH2O, among which are hydrates where n can be 5 (chromium(III) chloride pentahydrate CrCl3·5H2O) or 6 (chromium(III) chloride hexahydrate CrCl3·6H2O). The anhydrous compound with the formula CrCl3 are violet crystals, while the most common form of the chromium(III) chloride are the dark green crystals of hexahydrate, CrCl3·6H2O. Chromium chlorides find use as catalysts and as precursors to dyes for wool.

<span class="mw-page-title-main">Iridium(III) chloride</span> Chemical compound

Iridium(III) chloride is the inorganic compound with the formula IrCl3. The anhydrous compound is relatively rare, but the related hydrate is much more commonly encountered. The anhydrous salt has two polymorphs, α and β, which are brown and red colored respectively. More commonly encountered is the hygroscopic dark green trihydrate IrCl3(H2O)3 which is a common starting point for iridium chemistry.

<span class="mw-page-title-main">Gold(III) chloride</span> Chemical compound

Gold(III) chloride, traditionally called auric chloride, is an inorganic compound of gold and chlorine with the molecular formula Au2Cl6. The "III" in the name indicates that the gold has an oxidation state of +3, typical for many gold compounds. It has two forms, the monohydrate (AuCl3·H2O) and the anhydrous form, which are both hygroscopic and light-sensitive solids. This compound is a dimer of AuCl3. This compound has a few uses, such as an oxidizing agent and for catalyzing various organic reactions.

<span class="mw-page-title-main">Terbium(III,IV) oxide</span> Chemical compound

Terbium(III,IV) oxide, occasionally called tetraterbium heptaoxide, has the formula Tb4O7, though some texts refer to it as TbO1.75. There is some debate as to whether it is a discrete compound, or simply one phase in an interstitial oxide system. Tb4O7 is one of the main commercial terbium compounds, and the only such product containing at least some Tb(IV) (terbium in the +4 oxidation state), along with the more stable Tb(III). It is produced by heating the metal oxalate, and it is used in the preparation of other terbium compounds. Terbium forms three other major oxides: Tb2O3, TbO2, and Tb6O11.

<span class="mw-page-title-main">Scandium chloride</span> Chemical compound

Scandium(III) chloride is the inorganic compound with the formula ScCl3. It is a white, high-melting ionic compound, which is deliquescent and highly water-soluble. This salt is mainly of interest in the research laboratory. Both the anhydrous form and hexahydrate (ScCl3•6H2O) are commercially available.

<span class="mw-page-title-main">Gadolinium(III) chloride</span> Chemical compound

Gadolinium(III) chloride, also known as gadolinium trichloride, is GdCl3. It is a colorless, hygroscopic, water-soluble solid. The hexahydrate GdCl3∙6H2O is commonly encountered and is sometimes also called gadolinium trichloride. Gd3+ species are of special interest because the ion has the maximum number of unpaired spins possible, at least for known elements. With seven valence electrons and seven available f-orbitals, all seven electrons are unpaired and symmetrically arranged around the metal. The high magnetism and high symmetry combine to make Gd3+ a useful component in NMR spectroscopy and MRI.

<span class="mw-page-title-main">Ruthenium(III) chloride</span> Chemical compound

Ruthenium(III) chloride is the chemical compound with the formula RuCl3. "Ruthenium(III) chloride" more commonly refers to the hydrate RuCl3·xH2O. Both the anhydrous and hydrated species are dark brown or black solids. The hydrate, with a varying proportion of water of crystallization, often approximating to a trihydrate, is a commonly used starting material in ruthenium chemistry.

<span class="mw-page-title-main">Vanadium(III) chloride</span> Chemical compound

Vanadium(III) chloride describes the inorganic compound with the formula VCl3 and its hydrates. It forms a purple anhydrous form and a green hexahydrate [VCl2(H2O)4]Cl·2H2O. These hygroscopic salts are common precursors to other vanadium(III) complexes and is used as a mild reducing agent.

<span class="mw-page-title-main">Yttrium(III) chloride</span> Chemical compound

Yttrium(III) chloride is an inorganic compound of yttrium and chloride. It exists in two forms, the hydrate (YCl3(H2O)6) and an anhydrous form (YCl3). Both are colourless salts that are highly soluble in water and deliquescent.

<span class="mw-page-title-main">Lanthanum(III) chloride</span> Chemical compound

Lanthanum chloride is the inorganic compound with the formula LaCl3. It is a common salt of lanthanum which is mainly used in research. It is a white solid that is highly soluble in water and alcohols.

Lanthanide triflates are triflate salts of the lanthanides. These salts have been investigated for application in organic synthesis as Lewis acid catalysts. These catalysts function similarly to aluminium chloride or ferric chloride, but they are water-tolerant (stable in water). Commonly written as Ln(OTf)3·(H2O)9 the nine waters are bound to the lanthanide, and the triflates are counteranions, so more accurately lanthanide triflate nonahydrate is written as [Ln(H2O)9](OTf)3.

Lanthanide trichlorides are a family of inorganic compound with the formula LnCl3, where Ln stands for a lanthanide metal. The trichlorides are standard reagents in applied and academic chemistry of the lanthanides. They exist as anhydrous solids and as hydrates.

References

  1. 1 2 Knop, Osvald; Hartley, Jean M. (15 April 1968). "Refinement of the crystal structure of scandium oxide". Canadian Journal of Chemistry. 46 (8): 1446–1450. doi:10.1139/v68-236.
  2. Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN   0-19-855370-6
  3. Emeline, A. V.; Kataeva, G. V.; Ryabchuk, V. K.; Serpone, N. (1 October 1999). "Photostimulated Generation of Defects and Surface Reactions on a Series of Wide Band Gap Metal-Oxide Solids". The Journal of Physical Chemistry B. 103 (43): 9190–9199. doi:10.1021/jp990664z.
  4. Stotz, Robert W.; Melson, Gordon A. (1 July 1972). "Preparation and mechanism of formation of anhydrous scandium(III) chloride and bromide". Inorganic Chemistry. 11 (7): 1720–1721. doi:10.1021/ic50113a058.
  5. McCleverty, J.A. and Meyer, T.J., Comprehensive Coordination Chemistry II, 2003, Elsevier Science, ISBN   0-08-043748-6, Vol. 3, p. 99 ["Refluxing scandium oxide with triflic acid leads to the isolation of hydrated scandium triflate"]
  6. Mindat, http://www.mindat.org/min-42879.html