Relation between crystal structure and transition temperature of superconducting metals and alloys

Using the Roeser–Huber equation, which was originally developed for high temperature superconductors (HTSc) (H. Roeser et al., Acta Astronautica 62 (2008) 733), we present a calculation of the superconducting transition temperatures, T_c, of some elements with fcc unit cells (Pb, Al), some elements with bcc unit cells (Nb, V), Sn with a tetragonal unit cell and several simple metallic alloys (NbN, NbTi, the A15 compounds and MgB₂). All calculations used only the crystallographic information and available data of the electronic configuration of the constituents. The model itself is based on viewing superconductivity as a resonance effect, and the superconducting charge carriers moving through the crystal interact with a typical crystal distance, x. It is found that all calculated T_c-data fall within a narrow error margin on a straight line when plotting (2x)² vs. 1/T_c like in the case for HTSc. Furthermore, we discuss the problems when obtaining data for T_c from the literature or from experiments, which are needed for comparison with the calculated data. The T_c-data presented here agree reasonably well with the literature data.