Spatial variation of superconducting properties in a large grain of Y-Ba-Cu-O

We report positional dependence of superconducting properties in a Y-Ba-Cu-O single grain fabricated with a top seeded melt growth technique. It is found that the distributions of the second phase of Y₂BaCuO₅ (Y211) inclusions and the magnetic properties vary with position in a large sample. The peak effect is observed in the region where the volume fraction of the Y211 particles is low. The optimum oxygen-annealing temperature for achieving high critical current is also dependent on the position in a large bulk. The regional distributions of the microstructure and the properties are not arbitrarily scattered but reasonably depend on the spatial distributions of growth rate and growth direction in a large grain.