Abstract
The structures of Cu and Cu have been solved and refined from single-crystal x-ray diffraction data. The structures are essentially the same and have single Cu-O sheets separated by either Tl-O or Bi-O double layers. The Cu structure is tetragonal with Å and Å, and there are strictly flat Cu-O sheets. Cu has a lower-symmetry structure which may be approximated with an orthorhombic cell with Å, Å, and Å; however, this ignores superstructure reflections along both the and axes. The Tl-O layers are much more strongly bound to each other than are the Bi-O layers; thus, better conduction along the axis is expected for Cu relative to Cu. Superconducting transition temperatures of 9 and 90 K were observed for Cu and Cu, respectively.
- Received 30 March 1988
DOI:https://doi.org/10.1103/PhysRevB.38.225
©1988 American Physical Society