ac susceptibility and grain-boundary pinning strengths in YBa sub 2 Cu sub 3 O sub 7 minus. delta. and YBa sub 2 Cu sub 2. 985 Ag sub 0. 015 O sub 7 minus. delta

Journal Article · Tue May 01 00:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.8838· OSTI ID:6883828

Shinde, S L; Morrill, J; Goland, D; Chance, D A; McGuire, T ^[1]

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1. IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598 (USA)

Estimation of the relative flux-pinning strengths of the matrix and the grain boundaries in polycrystalline oxide superconductors contributes to the understanding of their superconducting properties. Such understanding is further enhanced if measurements can be compared with those from materials with lattice substitution and doped grain boundaries. The ac susceptibilities of polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and YBa{sub 2}Cu{sub 2.985}Ag{sub 0.015}O{sub 7{minus}{delta}} were measured as functions of temperature, ac-magnetic-field strength, and frequency. The presence of two loss peaks in the imaginary part of the susceptibility, {chi}{prime}{prime}, was confirmed by comparison of ac and dc measurements obtained on materials with different microstructures. One peak in {chi}{prime}{prime} was found to be associated with the matrix transition and the other, at lower temperatures, with weak-link behavior at grain boundaries. The model by K.-H. Mueller for the field dependence of the peaks was used to estimate and compare the pinning-force densities in the matrix and at weak links for both pure and Ag-substituted YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. In the temperature range (75--90 K) and field range (1--10 Oe, rms) studied, similar pinning forces, 6{times}10{sup 8} T A m{sup {minus}2}, for the matrix of the two materials were found, but the pinning-force densities at the weak links were higher for the Ag-substituted material by a factor of 1.5, i.e., 10{sup 4} T A m{sup {minus}2} for YBa{sub 2}Cu{sub 2.985}Ag{sub 0.015}O{sub 7{minus}{delta}} as compared to 6{times}10{sup 3} T A m{sup {minus}2} for YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}.

• OSTI ID: 6883828
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 41:13; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
GRAIN BOUNDARIES
MAGNETIC SUSCEPTIBILITY
COPPER OXIDES
YTTRIUM OXIDES
FREQUENCY DEPENDENCE
MAGNETIC FLUX
SILVER ADDITIONS
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CRYSTAL STRUCTURE
MAGNETIC PROPERTIES
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SILVER ALLOYS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties