Study of YBa sub 2 Cu sub 3 O sub 7 minus x thin films grown on single crystal SrTiO sub 3 : Not all high angle grain boundaries destroy J sub c

Conference · Thu Jan 25 04:00:00 EST 1990 · AIP Conference Proceedings (American Institute of Physics); (USA)

OSTI ID:6535643

Chan, Siu-Wai; Hwang, D M; Ramesh, R; Sampere, S M; Nazar, L ^[1]; Gerhardt, R; Pruna, P ^[2]

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1. Bellcore, Red Bank, NJ (USA)
2. Rutgers, The State University of New Jersey, Piscatway, NJ (USA)

The microstructure of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} films on (001) and (014) SrTiO{sub 3} is examined by x-ray diffraction, optical microscopy and cross-sectional transmission electron microscopy. The growth of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} in as-deposited films is extremely anisotropic resulting in plate-like grains with (001) surfaces. These types of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} grains, 90{degree}-misoriented from each other, are observed to grow on both (001) and (014) surfaces of single crystal SrTiO{sub 3} because in cubic SrTiO{sub 3} there are three equivalent {l angle}100{r angle} directions that the c-direction (001) of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} can align with. On (001) SrTiO{sub 3}, the (001) oriented platelets become dominant over the whole film due to the anisotropic growth-rates, while on (014) none of the three orientations dominates resulting in smaller grain size and smoother surface. The 3-fold degenerate epitaxy of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} on SrTiO{sub 3} results in near-{Sigma}1 grain boundaries with two 90{degree}-misoriented abutting crystals. These high angle yet crystallographically special boundaries are inevitably free of extraneous phases because of their low boundary energies and therefore, they provide intact connections between YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} grains throughout the film. While some extraneous phases do exist in these films, they are located away from the bounaries, and hence, are not damaging to superconducting transport. The argument agrees with the high critical current density measured (2{times}10{sup 6}A/cm{sup 2}) at 77 K for a YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} film on (014) SrTiO{sub 3} where the measured supercurrent had to pass through at least 10 such boundaries.

• OSTI ID: 6535643
• Report Number(s): CONF-891092--
• Conference Information: Journal Name: AIP Conference Proceedings (American Institute of Physics); (USA) Journal Volume: 199:1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
COPPER COMPOUNDS
COPPER OXIDES
CRITICAL CURRENT
CRITICAL TEMPERATURE
CRYSTAL STRUCTURE
CURRENT DENSITY
CURRENTS
DEPOSITION
ELECTRIC CURRENTS
ELECTRON MICROSCOPY
FILMS
GRAIN BOUNDARIES
HIGH-TC SUPERCONDUCTORS
MICROSCOPY
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTING FILMS
SUPERCONDUCTORS
SURFACE COATING
THERMODYNAMIC PROPERTIES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
TRANSMISSION ELECTRON MICROSCOPY
YTTRIUM COMPOUNDS
YTTRIUM OXIDES