HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF AS-GROWN, CRUSHED AND CLEAVED C-60 CRYSTALS

C-60 crystals grown by vapour transport may exhibit rough surfaces dep ending on the cooling conditions at the end of growth. The rough surfa ces are due to hillocks of about 0.1-0.3 mu m on {002} and {111} faces . Hillocks on {002} faces are square pyramids bounded by {111} surface s or surfaces deviating from {111}. Hillocks on {111} faces are triang ular pyramids bounded by stepped {111} surfaces. The density of crysta l defects in as-grown and cleaved crystals is much lower than in crush ed crystals. The high density of defects in crushed crystals is induce d by specimen preparation. HREM imaging and simulation has confirmed t hat the cleaved surfaces are clean and free of lattice relaxation.