The properties of superconducting Nb3Si

Superconducting Nb
3
Si has been made by the explosive compression of the high temperature, equilibrium tetragonal Ti
3
P phase, confirming the work of Pan and his associates at Kiev. The material has a broad superconducting transition with an onset
T_{c} \sim 18
K and a mid-point ∼16K. T
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 has been tentatively identified as having the A15 structure with a lattice parameter ∼5.12Å. The upper critical field H
c2
(0) is disappointingly low at 15.5-17 tesla; this is, however, not inconsistent with highly degraded A15 material.