Scandium oxide

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Scandium(III) oxide
__ Sc3+ __ O2−
Names
IUPAC name
Scandium(III) oxide
Other names
Scandia, scandium sesquioxide
Identifiers
3D model (
JSmol
)
ECHA InfoCard
 100.031.844 Edit this at Wikidata
UNII
  • InChI=1S/3O.2Sc
SMILES
  • O=[Sc]O[Sc]=O
Properties
Sc2O3
Molar mass 137.910 g/mol
Appearance White 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 four-colored diamondHealth 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

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).

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 Sc−O bond distances of 2.159–2.071 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

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

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

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]

References

  1. ^
    doi:10.1139/v68-236
    .
  2. ISBN 0-19-855370-6
  3. doi:10.1021/jp990664z
    .
  4. doi:10.1021/ic50113a058
    .
  5. 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
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