Determination of the critical current density of Bi(2223)/Ag tapes from magnetic measurements: peculiarities and problems in the interpretation

Abstract

Multifilamentary Bi(2223)/Ag tapes, prepared by the powder-in-tube technique, have been characterized by SQUID magnetometry at temperatures between 4.5 K and 85 K with the magnetic field applied both parallel and perpendicular to the conductor. By analysing measurements for H|| tape we evaluate the current density versus temperature and we compare it with that obtained by transport measurements. In such a way we clearly specify a temperature domain where the current density is limited by the grain boundaries and, on the contrary, where the current density is limited by the intrinsic properties of the material. The temperature dependence of the intragrain current density of the Bi(2223) phase has also been estimated. By analysing measurements for H|| tape the current density anisotropy and problems in the interpretation of the measurements related to the intrinsic grain misalignment are discussed.