Stoichiometry and superconductivity in single layer Bi2+xSr2−yCuO6+-δ

✍ Scribed by R.M. Fleming; S.A. Sunshine; L.F. Schneemeyer; R.B. Van Dover; R.J. Cava; P.M. Marsh; J.V. Waszczak; S.H. Glarum; S.M. Zahurak; F.J. DiSalvo

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 943 KB
• Volume: 173
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(91)90791-v

✦ Synopsis

An insulating polymorph with a composition close to Bi2Sr2CuO 6 complicates the synthesis of the single copper layer superconductor Bi2+xSr2_yCuO6e~. We concentrate on the region where the material is single phase in air synthesis (2.18 <x<2.29, 1.44 < y< 1.7 ). The physical properties from insulating to marginally conducting as the composition moves toward x=y= O. Like to two-layer compound, the material has a superlattice due to a buckling of the planar structure, however the superlanice coherence is degraded by defects at finite values ofx and y. Density measurements indicate that the nonstoichiometry of Bi2 +~Sr2_yCuO6_+ is not accompanied by the formation of a large number of vacancies. The insulating polymorph, Bi2Sr2CuO6, can be suppressed by synthesis in modest oxygen pressures (above 5-10 arm ). The result is a bulk superconductor ( Tc ~ 10 K).