Ordered structures in YBa/sub 2/Cu/sub 3/O/sub 7-y/, La/sub 2-x/Sr/sub x/CuO/sub 4-par. delta/ and related perovskites
Conference
·
OSTI ID:5489559
Electron microscopy and electron diffraction studies have been performed on the superconducting oxides YBa/sub 2/Cu/sub 3/O/sub 7-y/, GdBa/sub 2/Cu/sub 3/O/sub 7-y/ and La/sub 2-x/Sr/sub x/CuO/sub 4-par. delta/ as well as the related perovskites La/sub 2/CuO/sub 4/, Eu/sub 2/CuO/sub 4/ and Gd/sub 2/CuO/sub 4/. Extra reflections are commonly observed in all the cases. For example, in the 123 compounds, in situ heating leads to transformations from orthorhombic to tetragonal with a loss of twin structure; on cooling the oxygen vacancies re-order in the basal plane to give 1/3(100)* or 1/4(110)* diffraction spots. In tetragonal Eu/sub 2/CuO/sub 4/ and Gd/sub 2/CuO/sub 4/, the (001) diffraction patterns often have extra spots at 1/2(110)* or at 1/4(110)* positions. Extra spots are also observed in La/sub 2/CuO/sub 4/ (orthorhombic) but this is probably due to the space group being primitive rather than centered. These observations are discussed in terms of the ordering of oxygen vacancies in the Cu-O planes of the various perovskite structures. 6 figs.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5489559
- Report Number(s):
- LA-UR-88-569; CONF-880481-1; ON: DE88006461
- Country of Publication:
- United States
- Language:
- English
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Wed Jul 01 00:00:00 EDT 1987
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OSTI ID:5124194
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Related Subjects
36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
EUROPIUM COMPOUNDS
EUROPIUM OXIDES
GADOLINIUM COMPOUNDS
GADOLINIUM OXIDES
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MICROSCOPY
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
POINT DEFECTS
RARE EARTH COMPOUNDS
SCATTERING
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TWINNING
VACANCIES
YTTRIUM COMPOUNDS
YTTRIUM OXIDES
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
EUROPIUM COMPOUNDS
EUROPIUM OXIDES
GADOLINIUM COMPOUNDS
GADOLINIUM OXIDES
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MICROSCOPY
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
POINT DEFECTS
RARE EARTH COMPOUNDS
SCATTERING
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TWINNING
VACANCIES
YTTRIUM COMPOUNDS
YTTRIUM OXIDES