Tilt grain boundaries in YBa sub 2 Cu sub 3 O sub 7-x thin films

Conference · Sun Jul 01 04:00:00 EDT 1990

OSTI ID:6152003

Gao, Y; Bai, G; Chang, H L.M.; Merkle, K L; Lam, D J

Grain boundaries in YBa{sub 2}Cu{sub 3}O{sub 7-x} superconductor thin films grown on (001) MgO by metal-organic chemical vapor deposition (MOCVD) have been characterized using transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM). It was found that the YBa{sub 2}Cu{sub 3}O{sub 7-x} thin films were highly textured with the c axes, or (001) orientation, nearly parallel between grains and perpendicular to the MgO substrate. A majority of the grain boundaries are low-angle boundaries with a tilt angle, {theta}, less than 15{degree}. The low-angle boundaries appear to be strongly faceted on an atomic scale in such a way that the boundary planes tend to be parallel to the (100), (010), or (110) lattice planes in one of the adjacent grains. Almost all of the lattice planes, except for a number of distorted regions along the boundaries, are continuous across the boundaries from one grain to another, accommodating the misorientation with a slight bending of the lattice planes. The small-angle boundaries are shown to consist of arrays of dislocations. A domain structure, formed by the interchange of a and b axes has been observed in large grains. The domain boundaries are strongly faceted with the (100) and (010) lattice planes parallel to the boundaries. These observations on the atomic structure of boundaries, are used to discuss the effect of grain boundaries on superconductor properties in YBa{sub 2}Cu{sub 3}O{sub 7-x} thin films. 15 refs., 9 figs.

• Research Organization: Argonne National Lab., IL (USA)
• Sponsoring Organization: DOE/ER; NSF
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6152003
• Report Number(s): CONF-9005145-5; ON: DE91006088
• Country of Publication: United States
• Language: English

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
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEPOSITION
DISLOCATIONS
ELECTRON MICROSCOPY
FILMS
GRAIN BOUNDARIES
HIGH-TC SUPERCONDUCTORS
LINE DEFECTS
MICROSCOPY
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTING FILMS
SUPERCONDUCTORS
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES