Charge transfer: an alternative way to describe the superconducting properties of the A-15 structure

A new approach is given to describe the superconducting properties of the A-15 compounds. Using the notion of charge transfer and local character of the constituents of an alloy, an attempt is made to give a coherent picture of the superconducting properties of different A3X alloys. A correlation is found between the difference of the density of electrons at the limits of the Wigner-Seitz cell of the atoms in an alloy and its physical properties. If the transfer is proportional to this difference, the Tsub(c) variations of different A-15 alloys can be described. This model also predicts high Tsub(c) for 'hypothetical' A-15 alloys like Nb3Si, Nb3Te or Nb3Bi. (author)