Influence of a finite Tc on enhanced superconductivity near the metal/insulator transition

We adapted the BCS equation for T-c so that it applies to disordered conductors near the metal/insulator transition (MIT). The resulting expression for T-c as a function of the conductivity accounted quite well for several disparate classes of superconducting materials near the MIT [disordered metals, oxide conductors (including high-T-c superconductors), semiconducting materials, organic conductors, and C-60]. This function, however, was applicable only to situations for which T-c was zero in the pure limit-which was the case for the data chosen. This paper extends the model to the nonzero case and compares the predictions to the appropriate data.