When examined under a high-resolution transmission microscope (HRTEM), high
ly oriented pyrolitic graphite (HOPG), after ultrasound treatment, is found
to contain some bent graphitic sheets. These bent structures are ordered g
raphitic sheets, which have specific bend angles that are a multiple of 30
degrees (from 30 degrees to 180 degrees). We speculate that the creation an
d variation of bend angles is a result of interplay between the conformatio
n of sp(3)-like defects and the ultrasound wave impact.