元素物質における超伝導発現と臨界温度Tcの価電子パラメーターによる解釈

概要

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It has been tried to interpret the superconductivity and its critical temperature (Tc ) in the elemental substances by the orbital electronegativity of the s electron, (Z/r (s))1/2, which is defined by the pseudopotential radius of the s electron, r (s), and the valence, Z. Dependence of critical temperature (Tc ) on (Z/r (s))1/2 showed a convex curve with a maximum around (Z/r (s))1/2=2.0, except for several substances and it is found that the elemental substances with higher Tc such as Nb and Pb have a (Z/r (s) )1/2 value close to the threshold one corresponding to the change from metal to semiconductor. Many exceptional substances can be plotted close to the convex curve by considering the effect of the p electron or by changing the cohesion state from bulk to film, suggesting the increase of Tc value due to the increase of s- and/or p-characters, though the critical temperature for metastable elemental substances is not completely explained by the orbital electronegativity of the s electron.