Superconductivity of Nd_(1.85)Ce_(0.15)CuO_(4-y) by Electrochemical Oxidation

Superconductivity of n-type superconductor Nd_(1.85)Ce_(0.15)CuO_(4-y)(NCCO)by electrochemical oxidation is re ported for the first time and the cyclic voltammogram curve for NCCO as working electrode is presented.In vestigations indicate that after oxidation,superconductivity of NCCO is improved:Tc is raised from 20 K up to 26 K,the superconducting volume fraction is increased also.The valence electronic states of oxygen and copper in NCCO are studied by x-ray photoelectron spectroscopy.It is found that the Cu-2_(ps/2)peak shifts to the higher binding energy side about 0.4 e V,which indicates that the valence-state of copper ions is risen up after oxidation.These results imply that hole-carriers exist in n-type superconductor.