Characterization of the Low Temperature Superconductor Niobium Carbonitride

Niobium carbonitride´s superior radiation tolerance , coupled with the recently reported increase in its upper critical magnetic field when made nanocrystalline, increases its potential importance in future technological high-field superconductor applications. The maximum transition temperature for the composition NbC_0.3N_0.7 is ~17.8 K and its upper critical magnetic field is ~11 T; this increases to ~12 T for the composition NbC_0.2N_0.8,. Using solid-state processing, we have fabricated microcrystalline bulk niobium carbonitride with a transition temperature of ~ 7.6 K. A comprehensive characterization of this material, which includes susceptibility, resistivity, magnetization, heat capacity and XRD measurements is provided. Comparisons between the heat-treated material and the same material subjected to hot isostatic pressing are made so that the values of the intrinsic fundamental properties can be identified and their sensitivities to different fabrication processes determined.