Electrochemical Oxidation and Superconductivity of the System La_2-xA_xCuO_4+z (A=Cb, Pb)

Abstract

Superconductivity in La_2-xCd_xCuO_4+z(0≤x≤0.1) and La_2-xPb_xCuO_4+z(0≤x≤0.15) were studied. The solid solutions prepared under ambient pressure and high oxygen pressure showed only semiconducting property, although they have enough formal valence of copper such as +2.1-2.15. Strong oxidation by electrochemical treatment only brought about superconductivity at Tc=20-40K for La_2-xCd_xCuO_4+z and 15-20K for La_2-xPb_xCuO_4+z