Properties of superconducting Nb3Si

Superconducting Nb3Si was made by the explosive compression of the high temperature, equilibrium tetragonal Ti3P phase. The material has a broad superconducting transition with an onset T/sub c/ approximately 18K and midpoint approximately 16K. T/sub c/ is 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 was identified as having the A15 structure with a lattice parameter approximately 5.12A. The upper critical field H/sub c2/(0) is disappointingly low at 15.5 to 17 tesla; this is, however, not inconsistent with highly degraded A15 material.