Superconductivity in binary alloys

A diagram variant of the coherent potential approximation is developed for disordered A1-xBx alloys in the superconducting state, and equations of superconductivity theory valid for any impurity concentration and in the complete temperature region (0 ≤ T ≤ Tc) are obtained. The metal-insulator phase diagram in the normal state is constructed. The dependence of the transition temperature Tc on the impurity concentration is investigated, and it is shown that the nature of this dependence depends strongly on V0 = εA-εB (εA,B are the energies of the conduction electrons of the A and B atoms, respectively)