Characterization of defects in p-quaterphenyl single crystals

Crystals of p-quaterphenyl were studied by synchrotron white beam x-ray topography. Leaves with (001) as the primary facet were grown from toluene solution by the solvent temperature gradient method. These leaves were shown to twin along the (201) plane. Two types of twinning were observed, a macroscopic twinning where two halves of the leaf were folded along the b-axis by 36.4° and a microscopic twinning, where narrow lamellae occur along the (201) plane, resulting in a flat crystal. These lamellae appear as lines in x-ray topographs. A low density of both growth dislocations were observed originating at the twinning planes.