VOLTAMMETRIC MEASUREMENT OF THE CU(III) CU(II) RATIO AND OXYGEN-CONTENT IN YBA2CU3O7-X SUPERCONDUCTIVE MATERIALS WITH A CARBON-PASTE ELECTRODE/

The Cu(III)/Cu(II) content ratio of five YBa2Cu3O7-x high-temperature (T-c, ca. 95 K) superconductive materials prepared under various final heating conditions was determined by differential-pulse voltammetry i n an alkaline-supporting Samples were mixed into a carbon-paste electr ode and deposited onto a glassy-carbon surface. A simple calculation m ethod based on voltammetric recordings was used to evaluate the stoich iometric coefficient of oxygen, which is of major interest in the char acterization of the physical (conductive and superconductive) properti es of these compounds. The thus-obtained results were compared with th ose provided by classical iodometry. The influence of several instrume ntal and preparative analytical variables on the voltammograms were st udied.