Chemistry:Aluminium dodecaboride

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Aluminium dodecaboride
Names
IUPAC name
Aluminium dodecaboride
Other names
AlB12
Identifiers
3D model (JSmol)
EC Number
  • 234-924-2
Properties
AlB
12
Molar mass 156.714 g/mol[1]
Appearance Yellow to black solid[1]
Density 2.55 g/cm3[1]
Melting point 2,070 °C (3,760 °F; 2,340 K)[1]
insoluble
Solubility soluble in hot nitric acid (decomposes),[2]
soluble in nitric acid (decomposes),[3]
soluble in sulfuric acid (decomposes)[3]
Structure
Tetragonal (α-form)
Orthorhombic (β-form)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Aluminium dodecaboride (AlB
12
) is a superhard chemical compound with 17% aluminium content by weight.

It is the hardest boride of the aluminium-boron system, which also includes AlB
10
, AlB
4
, AlB
2
and AlB.

Properties

There are two crystalline forms, α-AlB
12
, and γ-AlB
12
. Both forms are very similar and consist of a framework with three-dimensional networks of B
12
and B
20
units.[4] The phase β-AlB
12
is now believed to be the ternary boride C
2
Al
3
B
48
.[5]

Preparation

The β-form can be prepared by the reaction of boron(III) oxide with sulfur and aluminium, then adding carbon to the mixture.

Uses

The extreme hardness of AlB
12
makes it a favorable component of PCBN inserts, which are mainly used in cutting and grinding to replace diamond or corundum.

See also

Footnotes

  1. ↑ 1.0 1.1 1.2 1.3 Haynes, William M., ed (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.45. ISBN 1439855110. 
  2. ↑ Martienssen, Werner; Warlimont, Hans (2005). Springer Handbook of Condensed Matter and Materials Data. Springer-Verlag. pp. 1025. ISBN 9783540443766. Bibcode: 2005shcm.book.....M. 
  3. ↑ 3.0 3.1 Rebekoff Reeve, Martin (1991) Method of producing an aluminium boride. EP 0130016 B1
  4. ↑ Higashi, Iwami (2000). "Crystal chemistry of α-AlB12 and γ-AlB12". Journal of Solid State Chemistry 154 (1): 168–176. doi:10.1006/jssc.2000.8831. Bibcode: 2000JSSCh.154..168H. 
  5. ↑ Matkovich, V. I; Giese, R. F; Economy, J (1965). "Phases and twinning in C2Al3B48 (β-AlB12)". Zeitschrift für Kristallographie 122 (1–2): 108. doi:10.1524/zkri.1965.122.1-2.108. Bibcode: 1965ZK....122..108M.