価電子パラメーターによる超伝導物質の2次元マッピング

概要

論文の詳細を見る
Two dimensional mappings on superconductive elements A and AB compounds are constructed by using the valence electron parameters (the difference between pseudopotential radii (r (s), r (p) and r (d)) of s and p electrons or of s and d electrons, Δ(sp) or Δ(sd), and the orbital electronegativity of s electron, χ(s)=(Z/r (s))1/2, where Z is valence) as the coordinates. From the relation of band gap against χ(s), the change of metal to semiconductor in sp-bonded elemental substances occurs at the threshold value of (Z/r (s))1/2=2.098. It is found that the boundary for superconductivity in sp-bonded elemental substances and AB compounds appears around (Z/r (s))1/2≈2.3. On the other hand, superconductivity appears in the region with higher (Z/r (s))1/2 value in the transition metals and AB compounds containing transition metals. Lower limit in the abscissa scale is observed around (Z/r (s))1/2=1.3, suggesting the limitation due to electron density in metallic substances and AB compounds. Non-superconducting late 3d transition elements are clearly divided by a polynomial curve. Non-superconducting sp-bonded AB compounds are well separately placed in the region with higher (Z/r (s))1/2 value than 2.3 and lower Δ(sp) value than 0.150.