FIZIKA A 3 (1994) 1, 35-46

GRAIN SIZE DISTRIBUTION OF THE YBa₂Cu₃O_7-x HIGH TEMPERATURE SUPERCONDUCTING COMPOUND

DRAGO KUNSTELJ
Department of Physics, Faculty of Science, University of Zagreb, POBox 162, 41001 Zagreb, Croatia

Received 22 April 1994

The grain size distributions of three YBa₂Cu₃O_7-x ceramic samples, annealed at 960^° C for different times (t=7, 70 and 700 hours, respectively), have been investigated. Both the average grain size (r) and that in the longest dimension of the grain (l) have been measured. The ratio l/r (reflecting the deviation from the spherical shape) initially increases with the annealing time (t) but tends to decrease at elevated t. An approximate t^1/2 increase of l probably reflects a plate-like shape of grains. For all samples the distributions of r and l are fitted best with the log-normal (Gauss) grain size distribution. The correlation between the grain size and critical current distributions is briefly discussed.

UDC 538.91
PACS 74.72.Bk

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