hexagonal graphite

https://doi.org/10.1351/goldbook.H02818
The thermodynamically @[email protected] form of @[email protected] with an ABAB stacking @[email protected] of the @[email protected] The exact crystallographic description of this allotropic form is given by the space group \(d_{6h}^{4} - P6_{3}/\text{mmc}\) (@[email protected] constants: \(a=245.6\ \mathrm{pm}\), \(c=670.8\ \mathrm{pm}\)). Hexagonal @[email protected] is thermodynamically @[email protected] below approximately \(2600\ \text{K}\) and \(6\ \text{GPa}\).
Note:
The use of the term @[email protected] instead of the more exact term hexagonal @[email protected] may be tolerated in view of the minor importance of @[email protected], the other allotropic form.
Source:
PAC, 1995, 67, 473. (Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)) on page 494 [Terms] [Paper]