Structure and physical properties of single crystals of the 84-K superconductor Bi2.2Sr2Ca0.8Cu2O8+δ

Single crystals of the 84-K superconductor Bi_2.2Sr₂Ca_0.8Cu₂O_8+δ were characterized by x-ray diffraction, dc magnetic susceptibility, electrical resistivity, and microwave absorption. The structure has [CuO₂]_∞ 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 ρ_RT=130 μΩ cm. Initial results on Pb substitution yielding T_c's of 107 K are reported.