Development of rectangular Bi(2223) wires with reduced anisotropy

Ag-sheathed multifilamentary Bi(2223) wires have been prepared with a new rectangular configuration of the filaments conceived in order to reduce the effect of anisotropy on the transport properties at the liquid nitrogen temperature. At present, critical current densities at 77 K of 20.5 kA cm(-2) have been achieved on rectangular rolled wires of 0.6 x 0.9 mm(2) cross-section. The transport properties have been measured as a function of the applied field and of its orientation with respect to the wire. The new rectangular wires have shown a clearly reduced anisotropy compared to that of monofilamentary Bi(2223) tapes with a j(c) value of 34.5 kA cm(-2), which have been measured as a reference. With respect to standard tapes, where j(c) vanishes at a magnetic field of 0.5 T applied along the tape normal, the newly developed wires show considerable advantages: regardless of the orientation of the field, j(c) of rectangular wires vanishes at fields exceeding 0.8 T at 77 K.