New high-temperature superconductor: Bi/sub 2/Sr/sub 3-x/Ca/sub x/Cu/sub 2/O/sub 8+y/

Journal Article · Fri Feb 26 04:00:00 EST 1988 · Science (Washington, D.C.); (United States)

DOI:https://doi.org/10.1126/science.239.4843.1015· OSTI ID:6866612

Subramanian, M A; Torardi, C C; Calabrese, J C; Gopalakrishnan, J; Morrissey, K J; Askew, T R; Flippen, R B; Chowdhry, U; Sleight, A W

A new superconductor that displays onset behavior near 120 K has been identified as Bi/sub 2/Sr/sub 3-x/Ca/sub x/Cu/sub 2/O/sub 8+y/ with x ranging from about 0.4 to 0.9. Single crystal x-ray diffraction data were used to determine a pseudo-tetragonal structure based on an A-centered orthorhombic subcell with a = 5.399 A, b = 5.414 A, and c = 30.904 A. The structure contains copper-oxygen sheets as in La/sub 2/CuO/sub 4/ and YBa/sub 2/Cu/sub 3/O/sub 7/, but the copper-oxygen chains present in YBa/sub 2/Cu/sub 3/O/sub 7/ do not occur in Bi/sub 2/Sr/sub 3-x/Ca/sub x/Cu/sub 2/O/sub 8+y/. The structure is made up of alternating double copper-oxygen sheets and double bismuth-oxygen sheets. There are Ca/sup 2 +/ and Sr/sup 2 +/ cations between the adjacent Cu-O sheets; Sr/sup 2 +/ cations are also found between the Cu-O and Bi-O sheets. Electron microscopy studies show an incommensurate superstructure along the a axis that can be approximated by an increase of a factor of 5 over the subcell dimension. This superstructure is also observed by x-ray diffraction on single crystals, but twinning can make it appear that the superstructure is along both a and b axes. Flux exclusion begins in our samples at about 116 K and is very strong by 95 K. Electrical measurements on a single crystal of Bi/sub 2/Sr/sub 3-x/Ca/sub x/Cu/sub 2/O/sub 8+y/ show a resistivity drop at about 116 K and apparent zero resistivity at 91 K. 7 references, 5 figures, 2 tables.

• Research Organization: E. I. du Pont de Nemours and Co., Wilmington, DE (USA)
• OSTI ID: 6866612
• Journal Information: Science (Washington, D.C.); (United States), Journal Name: Science (Washington, D.C.); (United States) Vol. 239; ISSN SCIEA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALINE EARTH METAL COMPOUNDS
BISMUTH COMPOUNDS
CALCIUM COMPOUNDS
CHEMICAL PREPARATION
COHERENT SCATTERING
COPPER COMPOUNDS
CRYSTAL STRUCTURE
CRYSTALS
DATA
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EXPERIMENTAL DATA
INFORMATION
MOLECULAR STRUCTURE
MONOCRYSTALS
NUMERICAL DATA
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SCATTERING
STRONTIUM COMPOUNDS
SUPERCONDUCTIVITY
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION