Effect of crystal lattice defects on T c of transition metals (a review)

We present an overview of some theoretical models that describe variations of the superconducting transition temperature Tc and of the electron-phonon coupling constant in metals with crystal lattice defects of various types. We analyze results of experimental studies of the influence of the defect structures, brought about by deformation at T ≃ 300 K and T ≪ Θ (Θ being the Debye temperature), on the Tc of transition metals with bcc (Nb, V, Ta) and hep (Re, Zr) lattices. Results of theoretical calculations are compared with experimental data on Tc in Nb with high dislocation densities. We report results of numerical computations of a few microscopic characteristics that control the superconducting parameters of transition metals with deformation-induced defects.