Microstructure and Critical Current Densities of Mo-sheathed PbMo_6S_8 Wires : High Transport J_c Achieved by HIP Treatments(Low-T_c Superconducting Materials Research)

Microstructure and superconducting properties of PbMo_6S_8 wires with Mo barriers were investigated. First, these Mo-sheathed wires were heat treated at ambient pressure, and a transport critical current density, J_c, of greater than 10^8 A/m^2 at 8 T and 4.2 K was observed. The microstructure of the PbMo_6S_8 core in these wires is porous, and transport current flows percolatively through the poor connections between the PbMo_6S_8 grains. Then it was revealed that hot-isostatic-pressing (HIP) treatments are very effective for densifying the microstructure of PbMo_6S_8 and improving the transport J_c. For the first time, J_c values of approximately 10^8 A/m^2 at 22-23 T (4.2 K), which are of the order of the highest J_c Values so far reported, were reproducibly observed in HIP-treated, Mo-sheathed PbMo_6S_8 wires