Large single-grain bulk RE-Ba-Cu-O (RE: rare earth elements) superconductors with high Jc values can trap magnetic fields much greater than conventional permanent magnets. At present, the maximum trapped fields are essentially limited by the mechanical property of RE-Ba-Cu-O, and therefore, its improvement is critically important. In this study, we measured mechanical properties of large-grain Y-Ba-Cu-O and Sm-Ba-Cu-O bulk superconductors by monitoring the strain with the gauges directly mounted onto the sample surface. The stress was applied to the samples by reducing the external field from 10 to 0 T at 50 K. It is found that the present strain gauge method is useful for direct characterization of mechanical properties of large grain materials. It is also confirmed that Ag addition is effective in improving the mechanical properties of large block Y-Ba-Cu-O and Sm-Ba-Cu-O.
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