Aluminium dodecaboride

Aluminium dodecaboride

Names
IUPAC name Aluminium dodecaboride
Other names AlB12
Identifiers
CAS Number	12041-54-2^Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.031.737
EC Number	234-924-2
PubChem CID	6336895
InChI InChI=1S/Al.12B Key: JXOOCQBAIRXOGG-UHFFFAOYSA-N
SMILES [B].[B].[B].[B].[B].[B].[B].[B].[B].[B].[B].[B].[Al]
Properties
Chemical formula	AlB12
Molar mass	156.714 g/mol[1]
Appearance	Yellow to black solid[1]
Density	2.55 g/cm^3[1]
Melting point	2,070 °C (3,760 °F; 2,340 K)[1]
Solubility in water	insoluble
Solubility	soluble in hot nitric acid (decomposes),[2] soluble in nitric acid (decomposes),[3] soluble in sulfuric acid (decomposes)[3]
Structure
Crystal 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). N verify (what is ^YN ?) Infobox references

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

• Boron
• Aluminium boride

Footnotes

1. Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, Florida: CRC Press. p. 4.45. ISBN 1-4398-5511-0.
2. Martienssen, Werner; Warlimont, Hans (2005). Martienssen, Werner; Warlimont, Hans (eds.). Springer Handbook of Condensed Matter and Materials Data. Springer-Verlag. p. 1025. Bibcode:2005shcm.book.....M. ISBN 9783540443766.
3. 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. Bibcode:2000JSSCh.154..168H. doi:10.1006/jssc.2000.8831.
5. Matkovich, V. I; Giese, R. F; Economy, J (1965). "Phases and twinning in C₂Al₃B₄₈ (β-AlB₁₂)". Zeitschrift für Kristallographie. 122 (1–2): 108. Bibcode:1965ZK....122..108M. doi:10.1524/zkri.1965.122.1-2.108.

External links

• "Boron";
• "Lightness and hardness"