Electrochemical Behavior of High Transition Temperature Superconducting Oxides

Abstract

Typical high transition temperature (high-Tc) superconducting oxides were used as electrodes in order to investigate their electrochemical behavior at room temperature. Chemical stability of these materials in various solutions was also tested. These superconducting oxides were stable in nonaqueous solutions, but is was very difficult to protect electrical contacts from the solvents because of porous structures of these oxides. These materials were rather stable in highly concentrated alkaline solutions while unstable in neutral and acid solutions. Electrochemical experiments were carried out in alkaline solutions, and the following results were obtained: (1) All of the high-Tc superconducting oxides were unstable at cathodic polarization. (2) Oxygen evolution was observed under anodic polarization. (3) These oxides behaved like p-type semiconductros though no photocurrents were detected. (4) [Fe(CN)6]3−⁄4− served as a redox couple for all of these high-Tc oxides.

Voltammetric Measurement of the Cu(III)/Cu(II) Ratio and Oxygen Content in YBa2Cu3O7-x Superconductive Materials with a Carbon-Paste Electrode

“…[2][3][4][5][6][7][8][9][10][11] In addition, some authors have found some of these methods to be suitable for determining the Cu(III)/ Cu(II) ratio. By using a rotating ring-disk electrode, Rosamilia et al investigated a YBaCuO superconductor that was placed on a disk in various acidic solutions.12 Other authors have used cyclic voltammetry to measure the Cu(III) content in highly alkaline aqueous solutions' 3,14 and non-aqueous media.15,16 Other electroanalytical methods used for this purpose include chronopotentiometry" and coulometric titratlons.l8, 19 The carbon-paste electrode is another useful approach to the problem.…”