The properties of superconducting Nb3Si

Superconducting Nb3Si has been made by the explosive compression of the high temperature, equilibrium tetragonal Ti3P phase, confirming the work of Pan and his associates at Kiev. The material has a broad superconducting transition with an onsetTc ~ 18K and a mid-point ∼16K. Tcis considerably reduced by fast neutron irradiation but can be partially recovered by annealing at 600°C. X-ray results are inconclusive but the new superconducting phase has been tentatively identified as having the A15 structure with a lattice parameter ∼5.12Å. The upper critical field Hc2(0) is disappointingly low at 15.5-17 tesla; this is, however, not inconsistent with highly degraded A15 material.