Observation of the High-Tc Phase and Determination of the Pb Position in a Bi-Pb-Sr-Ca-Cu Oxide Superconductor

The high-T c phase of a Bi-Pb-Sr-Ca-Cu oxide superconductor was observed directly by high-resolution transmission electron microscopy (HREM), and the atomic positions of Pb in the crystal were determined by high-resolution analytical electron microscopy (HRAEM) with a high spatial resolution 17 Å using a probe 5 to 10 Å in diameter. The HREM observation revealed that the crystal consisted solely of a triple Cu-O layered structure with c/2=18 Å and without any intergrowth, and that the crystal structure was modulated along the b-axis. The HRAEM indicated that the Pb atoms were located in the Bi-O layers with an atomic ratio of Pb/Bi∼0.1.