Single crystal sof the 84-K superconductor ${\mathrm{Bi}}_{2.2}{\mathrm{Sr}}_2{\mathrm{Ca}}_{0.8}{\mathrm{Cu}}_2{\mathrm{O}}_{8+\delta }$ were characterized by x-ray diffraction, dc magnetic susceptibility, electrical resistivity, and microwave absorption. The structure has ${\left[\mathrm{Cu}{\mathrm{O}}_2\right]}_{\infty }$ planes separated by calcium atoms, edge-shared bismuth oxide double layers, and an incommensurate superlattice along $b$ with a period of 4.76. The in-plane resistivity above $T_c$ is linear in $T$, with ${\rho }_{\mathrm{RT}}=130\mathrm{}$ μΩ cm. Initial results on Pb substitution yielding $T_c\text{'}\mathrm{s}$ of 107 K are reported.

• Received 12 February 1988

DOI:https://doi.org/10.1103/PhysRevB.38.893