The material aspect in advanced superconducting wires

The industrial development of multifilamentary superconducting wires has in the past been essentially concentrated on the two cubic materials (NbTi and Nb₃Sn), which can be produced in continuous filaments. Progress on Nb₃Sn wires was obtained by substituting ternary additives (magnetic fields<14 T) or by using composite cores (magnetic fields=10-12 T). The current density of Nb₃Sn wires has been found to vary quite strongly when applying axial and transverse stresses. More recently, monofilamentary wires of complex, noncubic phases such as PbMo₆S₈ (rhombohedral), and YBa₂Cu₃O₇ (orthorhombic), have been prepared by powdermetallurgical processes. A brief review of the state of art in producing wires of the various systems if given, with particular emphasis on the material aspect of the current-carrying capacity.