Transmission electron microscopy study on the annealing of YBa sub 2 Cu sub 3 O sub 7 minus. delta

Journal Article · Tue May 01 04:00:00 EDT 1990 · Journal of the American Ceramic Society; (USA)

DOI:https://doi.org/10.1111/j.1151-2916.1990.tb05173.x· OSTI ID:6072077

Monteiro, O R ^[1]; Johnson, S M ^[2]

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1. Lawrence Berkeley Lab., CA (USA). Materials and Chemical Sciences Div.
2. SRI International, Menlo Park, CA (USA)

Anneal in oxygen-rich atmosphere at temperatures between 400{degrees} and 600{degrees} C is an important step in the manufacture of superconducting YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. The symmetry of the orthorhombic phase requires that if more than one type of twin plane is present within a grain, a distorted region should exist inside the multiple twinned grain. This distorted region hinders the tetragonal-to-orthorhombic transformation and may account for some retained tetragonal phase inside an otherwise orthorhombic grain. A physical model is presented describing the formation of such regions and their eventual transformation into low-angle grain boundaries after long annealing. Extended annealing at intermediate temperatures apparently leads to the formation of planar faults in off-stoichiometric samples. Transmission electron microscope image contrast and energy dispersive x-ray analyses of highly defective regions suggest these defects are CuO{sub {ital x}} ({ital x} = 1,2) extra layers. These extra layers tend to from near grain boundaries or free surfaces, where oxygen is readily available.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6072077
• Journal Information: Journal of the American Ceramic Society; (USA), Journal Name: Journal of the American Ceramic Society; (USA) Vol. 73:5; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
426001 -- Engineering-- Superconducting Devices & Circuits-- (1990-)
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
ANNEALING
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON MICROSCOPY
ELEMENTS
GRAIN BOUNDARIES
HEAT TREATMENTS
HIGH-TC SUPERCONDUCTORS
MANUFACTURING
MICROSCOPY
MICROSTRUCTURE
NONMETALS
ORTHORHOMBIC LATTICES
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SPECTRA
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY SPECTRA
YTTRIUM COMPOUNDS
YTTRIUM OXIDES