NEW SHEAR-LIKE STRUCTURE - THE 2212-RELATED CUPRATE BI16SR28CU17O69+DELTA

The strategy of shearing mechanism has been applied to the 2212 bismuth cuprate Bi2Sr2CaCu2O8. A new compound has been synthesized, Bi16Sr28Cu17O69+delta; it crystallizes in a monoclinic cell with a = 48.40 (1) Angstrom, b = 5.495 (1) Angstrom, c = 16.283 (4) Angstrom, and beta = 109.96 (2)degrees. This phase exhibits 2212 ribbons running along c that are 9 Bi atoms wide, and shifted by 5.3 Angstrom with respect to each other; these ribbons are interconnected through thin layers involving CuO6 octahedra. In spite of its close relations with an ideal (101)-shear ''2212'' structure, this cuprate cannot be considered as such and is termed (101)-collapsed ''2212'' cuprate in agreement with previous works on (010)-collapsed ''2201'' cuprates. The rupture of the [CuO2](infinity) layers and the possibility of using these phenomena for creating columnar defects in high-T-c superconducting cuprates are also discussed. (C) 1995 Academic Press, Inc.