Current capability of filaments depending on their position in (Bi,Pb)2Sr2Ca2Cu3O10+δ ‐multifilament tapes

The microstructures of single filaments of silver‐sheathed (Bi,Pb)2Sr2Ca2Cu3O10+δ‐multifilament tapes are investigated by polarized light and scanning electron microscopy. Large differences in the microstructure of filaments depending on their position in the cross section of the tape are found. The influence of this microstructure on the critical current density is investigated by magneto‐optics. A drastic reduction of the critical current density by a factor of about 10 of the outer, compared to the filaments in the center of the tape is observed.