Study on the superconductivity of Ba sub 2 (Y sub 1 minus x La sub x )Cu sub 3 O sub 7 minus y
- Inst. of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing (CN)
This paper reports on a series of samples with the nominal composition Ba{sub 2}(Ba{sub 1{minus}x}La{sub x})Cu{sub 3}O{sub 7{minus}y}, (O {le} x {le} 1), that was synthesized by solid state reaction. An X-ray diffraction study showed that a continuous solid solution exists between Ba{sub 2}YCu{sub 3}O{sub 7{minus}y} and Ba{sub 2}LaCu{sub 3}O{sub 7{minus}y} and there is a composition induced order-disorder transition from an orthorhombic to a tetragonal structure when x value is near 0.9. All the samples with orthorhombic crystal structure are superconductors with T{sub c} onset above 90 K. The transition midpoint temperature decreases smoothly when La content increases. The samples with x {ge} 0.9 have a tetragonal structure and show semiconductor behavior with an exception of the x = 1.0 sample which is a superconductor. Based on our previous and present studies, we concluded that the low dimensional character of the crystal structure and the mixed-valence state of copper or oxygen are necessary conditions for high-T{sub c} superconductivity in copper-containing oxides.
- OSTI ID:
- 5338506
- Journal Information:
- International Journal of Modern Physics B; (United States), Journal Name: International Journal of Modern Physics B; (United States) Vol. 2:3; ISSN 0217-9792; ISSN IJPBE
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COHERENT SCATTERING
COPPER
COPPER COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUPRATES
DIFFRACTION
DISPERSIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
HIGH-TC SUPERCONDUCTORS
LANTHANUM COMPOUNDS
METALS
MIXTURES
NONMETALS
ORDER-DISORDER TRANSFORMATIONS
ORTHORHOMBIC LATTICES
OXYGEN
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
SOLID SOLUTIONS
SOLIDS
SOLUTIONS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
SYNTHESIS
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VALENCE
X-RAY DIFFRACTION
YTTRIUM COMPOUNDS