Correlation between valence electron concentration and high-temperature superconductivity Original Research Article

In this paper we study the correlation between valence electron concentration (VEC) and the critical temperature for various types of high-temperature superconductors. It is found that for a certain class of compounds the TC values are higher as the VEC valence parameter gets closer to VEC=4. The TC versus VEC linear curve extrapolation indicates the possible maximum TC value which could be theoretically obtained for Bi- and Tl-based superconductors with more than n=3 Cu–O planes in their structure. The influence of the oxygen content in YBCO and BSCCO superconductors and some substitution effects are also discussed in the TC–VEC correlation terms.