Characterization of defects in p-terphenyl single crystals

White Beam Synchrotron X-ray Topography has been used to characterize defects in solution-grown p-terphenyl single crystals. Defects observed include growth dislocations, mechanically introduced dislocations, macroscopic twins, twin lamellae, and dislocations emitted from twin boundaries. Line direction and Burgers Vector analysis of the growth and mechanically introduced dislocations, using projective geometry calculations and g · b analysis, respectively, are presented, along with complete analysis of the twin operation, obtained from a combination of analysis of optical micrographs and of orientation contrast on synchrotron topographs. The relationship between the Burgers vector of the dislocations generated at the twin boundary and the strain associated with the twins is discussed. Interesting interactions between mechanically introduced dislocations and twin boundaries are presented. Defect analyses are discussed in the context of results obtained previously using transmission electron microscopy.