The structure of the 44 K superconductor (Y sub 1-x Ca sub x )Ba sub 2 Cu sub 3 O sub 6+. delta. (. delta. le 0. 2)

Journal Article · Tue Oct 31 23:00:00 EST 1989 · Journal of Solid State Chemistry; (USA)

DOI:https://doi.org/10.1016/0022-4596(89)90068-6· OSTI ID:7172064

Parise, J B; McCarron, III, E M ^[1]

---

1. E.I. Du Pont de Nemours and Co., Wilmington, DE (USA)

Replacing Y(III) by Ca(II) in (Y{sub 1-x}Ca{sub x})Ba{sub 2}Cu{sub 3}O{sub 6} induces superconductivity. A solid-solution limit exists, as is evidenced by the lack of variation in unit cell parameters for values of x > 0.3. At low nominal doping levels (x < 0.3), materials prepared by solid-state techniques consist of a complex intergrowth of Ca-rich and Ca-poor 123-type phases, as well as YBa{sub 2}Cu{sub 3}O{sub 6} and BaCuO{sub 2}. At higher nominal doping levels the Ca content of the 123-type phase becomes constant (x {approximately} 0.30). Structural refinements using data collected by X-ray and neutron powder diffractometry are consistent with Ca-doping causing oxidation only of Cu in the sheet, leaving the copper in the so-called chain site as Cu(I). Many of the structural changes occurring in this system upon oxidation, such as a flattening of the CuO{sub 2} sheets, a contraction of the in-plane Cu-O distance, and a decrease in the Cu-Cu distance between planes, also occur in the structurally related superconducting system, Pb{sub 2}Sr{sub 2}(Y{sub 1-x}Ca{sub x})Cu{sub 3}O{sub 8}.

• OSTI ID: 7172064
• Journal Information: Journal of Solid State Chemistry; (USA), Journal Name: Journal of Solid State Chemistry; (USA) Vol. 83:1; ISSN 0022-4596; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360000* -- Materials
360100 -- Metals &amp; Alloys
360104 -- Metals &amp; Alloys-- Physical Properties
360204 -- Ceramics
Cermets
&amp; Refractories-- Physical Properties
ALKALINE EARTH METALS
BARIUM
CALCIUM
CHALCOGENIDES
COHERENT SCATTERING
COMPOSITE MATERIALS
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
MATERIALS
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SUPERCONDUCTING COMPOSITES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
X-RAY DIFFRACTION
YTTRIUM