Effect of Lattice Disorder on the Superconducting Transition Temperature

A theory is presented to explain the dependence of the superconducting transition temperature $T_c$ on the changes in the phonon frequency spectrum and electronic density of states which result from lattice disorder. Numerical calculations of $T_c$ are presented for films composed of crystalline granules, for films composed of amorphous granules, and for homogeneous amorphous metals. The calculations are in good agreement with experimental values of $T_c$.