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

Multifilamentary Bi(2223)/Ag tapes, prepared by the powder-in-tube techniqu e, have been characterized by SQUID magnetometry at temperatures between 4. 5 K and 85 K with the magnetic field applied both parallel and perpendicula r to the conductor. By analysing measurements for H perpendicular to tape w e evaluate the current density versus temperature and we compare it with th at obtained by transport measurements. In such a way we clearly specify a t emperature domain where the current density is limited by the grain boundar ies and, on the contrary, where the current density is limited by the intri nsic properties of the material. The temperature dependence of the intragra in current density of the Bi(2223) phase has also been estimated. By analys ing measurements for H parallel to tape the current density anisotropy and problems in the interpretation of the measurements related to the intrinsic grain misalignment are discussed.