Superconducting transition temperature of ion bombarded niobium carbide surface layers

Abstract

The influence of Ge and C ion irradiation on the critical temperature of NbC layers obtained by the diffusion of C onto Nb-Ge-Cu substrate was studied. As a result of the irradiation with Ge ions of 150 keV and fluxes of 2.10¹⁵ and 2.10¹⁶ ion cm⁻², a slight decrease of the critical temperature, of 0.3 K and 0.6 K respectively, was observed. In both cases the critical temperature reached the pre-irradiation values after a thermal treatment for 24 h at 600° C. The irradiation with C ions of 170–180 keV and fluxes up to 2.10¹⁶ ions cm⁻² led to an increase by 30% of the critical temperature at low energies and to its degradation after the thermal treatment.