The resistivity and superconductivity of transition metals

A recently proposed and apparently successfully validated correlation between the temperature coefficient of resistivity for transition metals and β-W compounds and the characteristic coupling constant of superconductivity theory is re-examined. It is shown that the correlation implies that these materials may be regarded as a type of semi-metal, if a model is adopted in which the electrons occupy a free-electron-like band. A corresponding modification exists to the McMillan or similar expression for the critical temperature. (author)