Single crystals of hexamethylbenzene were grown from benzene or xylene solutions. Plates, ribbons, whiskers and rhombohedral blocks were observed, with prism planes of (100), (010), (001) and (110). The ribbons and plates had well-developed (100) or (001) planes, and grew along the (010) axis. Twinned crystals were also observed, with a composition plane and twin boundary of (001). Lattice defects in the crystals were investigated by means of X-ray topography, and dislocations with Burgers vectors of  [100], [010] and [¯110] were observed. The slip plane was (001). The dislocations with the shortest Burgers vector, [001], were not observed. The characteristics of these dislocations were explained in terms of the steric hindrance of molecules to slip.

K.Izumi: Journal of Crystal Growth, 1996, 169[2], 325-30