HRTEM Surface Profile Imaging of Superconducting YBa2Cu4O8

Surface profile images have been recorded from high-Tc superconducting YBa2Cu4O8 using high-resolution transmission electron microscopy. The surface regions are found to be relatively more stable than those of YBa2Cu3O7. The stability of the double CuO chains in the vicinity of a crystal surface was found to depend on whether or not they were parallel or perpendicular to the surface in question. Possible mechanisms of the formation of both surface structures and near-surface defects are discussed.