Aluminum dodecaboride

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General
Surname Aluminum dodecaboride
Molecular formula AlB 12
Brief description

shiny black

External identifiers / databases
CAS number 12041-54-2
EC number 234-924-2
ECHA InfoCard 100,031,737
PubChem 16212552
Wikidata Q4737382
properties
Molar mass 156.71 g mol −1
Physical state

firmly

density

2.56 g cm −3 (α form)

Melting point

2150 ° C

safety instructions
GHS labeling of hazardous substances
no GHS pictograms
H and P phrases H: no H-phrases
P: no P-phrases
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Aluminum dodecaboride is an intermetallic compound of aluminum from the group of borides .

Extraction and presentation

Aluminum dodecaboride can be obtained by reacting boron (III) oxide with sulfur and aluminum . If you add carbon to the mixture , the β-form is created.

properties

Alpha AlB12 icosahedron.png
Alpha AlB12 B19 unit.png


B 12 icosahedron (left) and B 19 unit in the crystal structures of α- and γ-AlB 12 .

Aluminum dodecaboride is a solid that comes in two forms. α-aluminum dodecaboride crystallizes tetragonal , space group P 4 3 2 1 2 (space group no.96) or P 4 1 2 1 2 ( no.92 ) , lattice parameters a = 1016 pm, c = 1427 pm), γ-AlB 12 is orthorhombic with the space group P 2 1 2 1 2 1 (No. 19) and the lattice parameters a = 1657 pm, b = 1751 pm and c = 1014 pm. Both phases have complicated structures, but they are composed of the same structural motifs: a B 12 - icosahedron and a B 19 unit. The latter consists of two incomplete icosahedra (one atom is missing in each case), which are connected by a common triangular surface. Both the B 12 and B 19 units are linked to neighboring groups by B – B bonds. The aluminum atoms are statistically distributed over several positions in the crystal structure. The boride previously described as β-aluminum dodecaboride crystallizes orthorhombically (a = 1234 pm, b = 1263 pm, c = 508 pm). It is not a pure boride, but a phase with the composition C 2 Al 3 B 48 . The latter is suitable as a starting product for the production of other borides in well-formed crystals. Template: room group / 96Template: room group / 92Template: room group / 19

See also

Individual evidence

  1. ↑ a b c d Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 789.
  2. ↑ a b Data sheet Aluminum dodecaboride, −325 mesh from Sigma-Aldrich , accessed on January 27, 2014 ( PDF ).
  3. ↑ Roger Blachnik (Ed.): Paperback for chemists and physicists . Volume III: Elements, Inorganic Compounds and Materials, Minerals . founded by Jean d'Ans, Ellen Lax. 4th, revised and revised edition. Springer, Berlin 1998, ISBN 3-540-60035-3 , pp. 292 ( limited preview in Google Book search).
  4. ^ I. Higashi: Crystal Chemistry of α-AlB 12 and γ-AlB 12 . In: Journal of Solid State Chemistry , 154, 2000, pp. 168-176, doi: 10.1006 / jssc.2000.8831 .
  5. ^ VI Matkovich, RF Giese, J. Economy: Phases and twinning in C 2 Al 3 B 48 (β-AlB 12 ). In: Zeitschrift für Kristallographie , 122 (1–2), 1965, pp. 108–115, doi: 10.1524 / zkri.1965.122.1-2.108 .