On the improvement of DyBa sub 2 Cu sub 3 O sub 7 minus. delta. properties through better sintering

Journal Article · Thu Feb 15 00:00:00 EST 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.345582· OSTI ID:6911383

Seuntjens, J M; Larbalestier, D C ^[1]

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1. Applied Superconductivity Center and Department of Materials Science and Engineering, University of Wisconsin, 1500 Johnson Drive, Madison, Wisconsin 53706 (US)

The sintering of DyBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} has been improved by controlling powder size, sintering temperature, and sintering atmosphere. Sintering below the eutectic temperature has been explored for different temperatures and oxygen partial pressures. Sintering kinetics have been enhanced, yielding high density (up to 95%) and small grain size (down to 1.5 {mu}m) with shorter sintering times and lower temperatures. Two sets of samples, one set containing 10-wt. % Ag{sub 2}O in the precursor powder and one undoped set, were studied. The sintering rate decreased with decreasing temperature, even in samples sintered in low partial pressures of oxygen (which increase the oxygen vacancy concentration). The addition of Ag{sub 2}O yielded a dispersion of Ag particles about one-half the DyBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} grain size at grain boundary triple points. Ag tended to enhance grain growth slightly and did not improve the superconducting properties. Resistivity was as low as 220 {mu}{Omega}-cm at 100 K. Transport critical current densities ({ital J}{sub {ital ct}}) were up to five times higher than in previous larger grain size samples that were sintered above the eutectic temperature. The best of the new samples achieved {similar to}100 A/cm{sup 2} at 4.2 K in fields of 1--7 T. This improvement occurred in spite of there being more than twice as much grain boundary surface area per unit volume. We conclude that the grain boundaries in sintered 123 compounds are not always barriers to current flow, and that increasing the proportion of nonbasal plane faced grain boundaries is important in raising {ital J}{sub {ital ct}}.

• OSTI ID: 6911383
• Journal Information: Journal of Applied Physics; (USA), Vol. 67:4; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
SINTERING
COPPER OXIDES
DYSPROSIUM OXIDES
CRITICAL CURRENT
ELECTRIC CONDUCTIVITY
GRAIN BOUNDARIES
SUPERCONDUCTIVITY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CRYSTAL STRUCTURE
CURRENTS
DYSPROSIUM COMPOUNDS
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FABRICATION
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication