Evidence for pinning by (Sr,Ca)2CuOy particles in partial-melting processed bulk Bi2Sr2CaCu2O8+δ ceramics

Flux distributions of partial-melting processed Bi2Sr2CaCu2O8 + delta ceramics are obtained using magneto-optic imaging. In remanent states (mu(0) H-a = 0 T), large amounts of trapped flux are observed along (Sr,Ca)(2)CuOy particles embedded in the Bi2Sr2CaCu2O8 (+) (delta) matrix. Despite the relatively large size of these particles (up to 30 mu m), the pinning effect is similar to that of Y2BaCuO5 particles in melt-processed YBa2Cu3O7 - delta. Furthermore, we discuss how the pinning capability of non-superconducting particles of different sizes and densities will show up in magneto-optic images. (C) 1998 Published by Elsevier Science B.V. All rights reserved.