Diagrammatic description of superconductivity in elements and AnB (n = 1, 2, 3) compounds based on pseudopotential radii

Highlights: ► Various superconducting materials can be two-dimensionally mapped. ► The orbital electronegativity and pseudopotential radii difference are taken as coordinates. ► The generation of superconductivity is closely related to the threshold for metal-semiconductor transition. ► The diagrammatic expression is available for the search of new superconducting materials. -- Abstract: Two dimensional diagrams for superconducting elements and AnB(n = 1, 2, 3) compounds have been constructed using the difference (ΔrENav) between Zunger's pseudopotential radii and the orbital electronegativity ([(Z/r(snpm))1/2]ENav) derived from the pseudopotential radii. It is found that both superconducting elements and AnB compounds are well placed in the same domain surrounded by four boundary lines in the ΔrENav-[(Z/r(snpm))1/2]ENav diagram. For sp-bonded elements, the boundary for superconducting/non-superconducting (SC/non-SC) is determined by a constant orbital electronegativity of [(Z/r(snpm))1/2]ENav≅2.3, which is close to the boundary ([(Z/r(snpm))1/2]ENav=2.046) for the metal–semiconductor transition. Superconducting elements and compounds with relatively high Tc values have an orbital electronegativity close to the value ranging between SC/non-SC and metal–semiconductor transition boundaries. It is suggested that arithmetically averaging of electronegativity is inadequate in AB-type transition metal nitrides and carbides