The critical current characteristic of a Y-Ba-Cu-O specimen prepared by the quench-and-melt growth (QMG) technique was investigated by the ac-inductive method. It was found that there were two kinds of currents. The bulk critical current density is 1.0×108A/m2at 77 K and 0.12 T. This value is comparable to a previous estimate from dc-magnetization measurements. The local current density amounts to 3.2×1010A/m2under the same conditions. Appearance of two kinds of currents seems to be caused by nonsuperconducting second-phase layers formed along the direction of grain growth, which disturb uniform current.
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