Defect structure and superconducting properties of La[sub 1. 8]Sr[sub [ital x]]Ca[sub 1. 2[minus][ital x]]Cu[sub 2]O[sub 6[minus][delta]]

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.12941· OSTI ID:6078125

Shaked, H; Jorgensen, J D; Hunter, B A; Hitterman, R L ^[1]; Kinoshita, K ^[2]; Izumi, F ^[3]; Kamiyama, T ^[4]

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1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Nippon Telegraph and Telephone Corporation Basic Research Laboratories, Musashino, Tokyo 180 (Japan)
3. National Institute for Research in Inorganic Materials, 1-1 Namiki, Tsukuba, Ibaraki 305 (Japan)
4. Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305 (Japan)

We have studied the relationship between structural defects and superconductivity in La[sub 1.8]Sr[sub [ital x]]Ca[sub 1.2[minus][ital x]]Cu[sub 2]O[sub 6[minus][delta]] (0[le][ital x][le]0.8). The samples were prepared by synthesis under different oxygen pressures, [ital P](O[sub 2])=50, 250, and 400 atm. Six of the seven samples were found to be superconducting with 22[le][ital T][sub [ital c]][le]58 K. The structural properties were determined by neutron powder diffraction. The inter-CuO[sub 2]-plane spacing, [ital d][sub Cu-Cu], increases as Ca on the [ital M](1) site between these planes is replaced by the larger Sr and La ions. The metal-site ordering is influenced by the oxygen pressure during synthesis. We have used the inter-CuO[sub 2]-plane spacing, neutron-diffraction measurements of the scattering from the metal sites, and chemical constraints to determine the occupancies of La, Sr, and Ca at the [ital M](1) site. For the same overall composition, higher oxygen pressure leads to a larger fraction of La on the [ital M](1) site. Oxygen occupancy of the vacant O(3) site in the [ital M](1) plane increases sharply when [ital d][sub Cu-Cu] exceeds 3.5 A. The superconducting transition temperature [ital T][sub [ital c]] decreases systematically as the occupancy of O(3) increases for samples that would otherwise be expected to be superconducting.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6078125
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 48:17; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360207 -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFRACTION
HIGH-TC SUPERCONDUCTORS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
NEUTRON DIFFRACTION
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE