An Empiricism for Establishing the Transition Temperatures of Superconducting Alloys and Compounds

The preparation of superconductive alloys may be guided by a form of empiricism based upon the isotope law. For a series of alloys having a common structure, the critical temperatures of its members are presumed so interrelated. The reduced mass of a compound becomes somewhat obscure for stoichiometry other than 50 to 50 at.%. Several possible definitions of reduced mass permit setting of upper and lower bounds on the transition point in general. Theoretical calculations are presented for Nb/sub 3/In with evidence that the experimental values for this substance and Nb/sub 3/Ga may require slight revision. In line with the quest for alloys with higher critical temperatures than N/b/sub 3/Sn, a prediction is made that Nb/sub 3/Si (were it to exist and be of the BETA - tungsten structure) would be a promising prospect. (auth)