Critical current distribution of hot isostatically pressed PbMo6S8 wires

Abstract

The ebMo6Ss Chevrel phase has an important potential for the construction of ultra-high-field superconducting coils. The critical current density of hot isostatically pressed (HIP) PbMorSs wires with a stainless steel matrix and a molybdenum diffusion barrier was investigated in fields up to 25 T. The field dependence of Jc is considerably improved in the high-field regime by going from a 990"C, 4 h to a 1225"C, 4 h HIP treatment at 110 MPa. However, a drop of Jc at unusually low fields as 15 T was observed. The appearance of a double peak in the critical current distribution, obtained by dV2/d/2 suggests that the origin of such a behavior is a strongly reduced effective upper critical field B*2, presumably at grain boundaries. A detailed analysis of the critical current distribution reveals that only a few percent of the wire is in a dissipative state at an electric field criterion of I ~t V cm-~, indicating that the used HIP parameters are not yet optimized.