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Correlation of transport and magnetic critical currents in melt-processed YBa<inf>2</inf>Cu<inf>3</inf>O<inf>7-δ</inf>thick films

Jones, AR and Cardwell, DA and Ingle, NJC and Ashworth, SP and Campbell, AM and Alford, NM and Button, TW and Wellhofer, F and Abell, JS (1994) Correlation of transport and magnetic critical currents in melt-processed YBa<inf>2</inf>Cu<inf>3</inf>O<inf>7-δ</inf>thick films. Journal of Applied Physics, 76. pp. 1720-1725. ISSN 0021-8979

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Abstract

Transport critical current measurements have been carried out on melt-processed thick films of YBa2Cu3O7-δon yttria-stabilized zirconia in fields of up to 8 T both within grains and across grain boundaries. These measurements yield Jcvalues of ∼3000 A cm-2at 4.2 K and zero magnetic field and 400 A cm-2at 77 K and zero magnetic field, taking the entire sample width as the definitive dimension. Optical and scanning electron microscopy reveals that the thick-film grains consist typically of a central "hub" region ∼50 μm in diameter, which is well connected to radial subgrains or "spokes" which extend ∼1 mm to define the complete grain structure. Attempts have been made to correlate the transport measurements of inter- and intra-hub-and-spoke (H-S) critical current with values of this parameter derived previously from magnetization measurements. Analysis of the transport measurements indicates that current flow through H-S grains is constrained to paths along the spokes via the grain hub. Taking the size of the hub as the definitive dimension yields an intra-H-S grain Jcof ∼60 000 A cm-2at 4.2 K and 0 T, which is in reasonable agreement with the magnetization data. Experiments in which the hub is removed from individual grains confirm that this feature determines critically the Jcof the film.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div C > Materials Engineering
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:11
Last Modified: 19 Jul 2018 08:16
DOI: