Enhanced high-field transport critical current density of superconducting bulk Y-Ba-Cu-O prepared by rapid solidification and directional annealing
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States)
- Department of Materials and Nuclear Engineering and Center for Superconductivity Research, University of Maryland, College Park, Maryland 20742-2115 (United States)
Strongly textured high-{ital T}{sub {ital c}} bulk Y-Ba-Cu-O was prepared with rapid solidification and directional annealing processes. Sintered YBa{sub 2}Cu{sub 3}O{sub 7} (1:2:3) samples, produced by conventional ceramic synthesis, were rapidly quenched with a twin rolling mill and directionally annealed by moving the sample at a speed of 0.2 cm/h through a temperature gradient of up to 60 {degree}C/cm from 1020 to 900 {degree}C. We have measured transport {ital J}{sub {ital c}} of 2000 A/cm{sup 2} by pulse current and 1150 A/cm{sup 2} by dc at 77 K in a field of 15 T. It has been found that the {ital J}{sub {ital c}} values measured by pulse and dc methods are approximately equal in high magnetic fields (8--15 T) and {ital J}{sub {ital c}} measured by pulse current is larger than that measured by dc in magnetic fields below 8 T. The measured values of {ital J}{sub {ital c}} decrease monotonically with increasing external magnetic field. Scanning and transmission-electron-microscopy studies showed that the 1:2:3 crystallites grow with their {ital c} axes perpendicular to the sample traveling direction. Crystallites of {similar to}2--4 {mu}m of Y{sub 2}BaCuO{sub 5} (2:1:1) phase were observed also with their {ital c} axes perpendicular to the sample traveling direction. Grains with twin crystals orientated at {similar to}90{degree} from each other were observed. Precipitates of CuO were observed using energy-dispersive x-ray analysis. Dislocations with a density of {similar to}5{times}10{sup 9}/cm{sup 2} were found in the 1:2:3 crystals. These dislocations lie on the {ital a}-{ital b} plane. The enhancement of {ital J}{sub {ital c}} probably is due to flux pinning by the dislocations and to the preferred orientation of the crystallites with the {ital a}-{ital b} plane parallel to the sample traveling direction.
- DOE Contract Number:
- FG02-84ER45174
- OSTI ID:
- 7049890
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Vol. 46:13; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARIUM OXIDES
CRITICAL CURRENT
COPPER OXIDES
YTTRIUM OXIDES
HIGH-TC SUPERCONDUCTORS
MAGNETIC FIELDS
MAGNETIC FLUX
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CURRENTS
ELECTRIC CURRENTS
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360207* - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)