Voltammetric Measurement of the Cu(III)/Cu(II) Ratio and Oxygen Content in YBa₂Cu₃O_7-x Superconductive Materials with a Carbon-Paste Electrode

Abstract

The Cu(III)/Cu(II) content ratio of five YBa₂Cu₃O_7-x high-temperature (T_c, ca. 95K) superconductive materials prepared under various final heating conditions was determined by differential-pulse voltammetry in an alkaline-supporting electrolyte (0.01M NaOH). Samples were mixed into a carbon-paste electrode and deposited onto a glassy-carbon surface. A simple calculation method based on voltammetric recordings was used to evaluate the stoichiometric coefficient of oxygen, which is of major interest in the characterization of the physical (conductive and superconductive) properties of these compounds. The thus-obtained results were compared with those provided by classical iodometry. The influence of several instrumental and preparative analytical variables on the voltammograms were studied.