Reversible axial-strain effect in Y-Ba-Cu-O coated conductors

Published

November 7, 2005

Author(s)

Najib Cheggour, John (Jack) W. Ekin, C. L. H. Thieme, Y Y. Xie, V Selvamanickam, Ron Feenstra

Abstract

The recently discovered reversible strain effect in Y-Ba-Cu-O (YBCO) coated conductors contrasts with the general understanding that the effect of strain on critical-current density J_c in practical high-temperature superconductors is determined only by crack formation in the ceramic component. Instead of having a constant J_c as a function of strain before an irreversible drop when cracks form in the superconductor, J_c in YBCO coated conductors can decrease or increase reversibly with strain over a significant strain range up to an irreversible strain limit. This reversible effect is present in samples fabricated either with rolling-assisted biaxially textured Ni-W substrates or with ion-beam-assisted deposition on Hastalloy substrates. The reversibility of J_c with strain is observed for thin as well as thick YBCO films, and at two very different temperatures (76 and 4K). The reversible effect is dependent on temperature and magnetic field, thus indicating its intrinsic nature. We also report an enhancement of the irreversible strain limit ε_irr where the reversible strain effect ends and YBCO cracking starts. The value of ε_irr increases from about 0.4% to more than 0.5% when YBCO coated conductors are fabricated with an additional Cu protection layer.

Citation

Superconductor Science and Technology

Volume

18

Pub Type

Journals

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Keywords

coated conductors, crack arresting, critical current, differential thermal contraction, fracture toughness, intrinsic strain effect, irreversible strain limit, pinning force, scaling, strain, superconductor, Y-Ba-Cu-O

Citation

Cheggour, N. , Ekin, J. , Thieme, C. , Xie, Y. , Selvamanickam, V. and Feenstra, R. (2005), Reversible axial-strain effect in Y-Ba-Cu-O coated conductors, Superconductor Science and Technology, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=32088 (Accessed November 21, 2024)