Preferred Label : rhombohedral graphite;
IUPAC definition : A thermodynamically unstable allotropic form of graphite with an ABCABC stacking sequence
of the layers. The exact crystallographic description of this allotropic form is given
by the space group D3d5 - R3(bar)m, (unit cell constants: a 256.6 pm, c 1006.2
pm).;
Scope note : the structure of rhombohedral graphite can be best considered as an extended stacking
fault in hexagonal graphite. rhombohedral graphite can not be isolated in pure form
(natural graphite and laboratory preparations contain less than 40% of rhombohedral
graphite in combination with hexagonal graphite). it is produced by shear deformation
of hexagonal graphite and transforms progressively to the hexagonal (abab) modification
on heating above 1600k.;
Origin ID : R05385;
See also
A thermodynamically unstable allotropic form of graphite with an ABCABC stacking sequence
of the layers. The exact crystallographic description of this allotropic form is given
by the space group D3d5 - R3(bar)m, (unit cell constants: a 256.6 pm, c 1006.2
pm).
