The arrangement of the oxygen atoms in high temperature superconductors is known to be critical to their properties. High resolution electron microscope imaging (HREM) accompanied by computer simulations has been anticipated to reveal the oxygen vacancies in the basal plane. Although images of sufficient resolution have been reported by many authors, the  and  projections have not been differentiated experimentally. We confirm here that they are clearly different using a specimen which contains a coherent grain boundary with (100), (001) in one grain parallel to (001), (010) in the second. Unfortunately we find that it is not possible to clearly answer the more important question of the oxygen content at the grain boundary.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics