Aluminium dodecaboride

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Aluminium dodecaboride
Names
IUPAC name
Aluminium dodecaboride
Other names
AlB12
Identifiers
3D model (
JSmol
)
ECHA InfoCard
 100.031.737 Edit this at Wikidata
EC Number
  • 234-924-2
  • InChI=1S/Al.12B
    Key: JXOOCQBAIRXOGG-UHFFFAOYSA-N
  • [B].[B].[B].[B].[B].[B].[B].[B].[B].[B].[B].[B].[Al]
Properties
AlB12
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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Aluminium dodecaboride (AlB12) is a

superhard chemical compound with 17% aluminium
content by weight.

It is the hardest boride of the aluminium-boron system, which also includes AlB10, AlB4, AlB2 and AlB.

Properties

There are two crystalline forms, α-AlB12, and γ-AlB12. Both forms are very similar and consist of a framework with three-dimensional networks of B12 and B20 units.[4] The phase β-AlB12 is now believed to be the ternary boride C2Al3B48.[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 AlB12 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. ^
    ISBN 1-4398-5511-0
    .
  2. ISBN 9783540443766
    .
  3. ^ a b Rebekoff Reeve, Martin (1991) Method of producing an aluminium boride. EP 0130016 B1
  4. doi:10.1006/jssc.2000.8831
    .
  5. doi:10.1524/zkri.1965.122.1-2.108
    .

External links
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