J(c)-B properties of large RE-Ba-Cu-O disks

We estimated J(c)-B characteristics based on the sand-pile model from the m agnetic field distribution on large disk samples with dimensions of 10 x 10 x 1 mm(3). Such thin disks Show a large demagnetizing effect. Thus simple estimates of J(c) from the field distribution failed to determine correct v alues, and a large discrepancy was observed with J(c) values determined fro m magnetization loops of small specimens. J(c)-B characteristics obtained f rom the sand-pile model were in good agreement with those obtained from sma ll specimens.