Coulometric determination of the average valencies of copper and bismuth in the superconducting bismuth-strontium-calcium-copper-oxygen system

Abstract

The average valencies of copper and bismuth in the superconducting Bi-Sr-Ca-Cu-O system have been determined using a coulometric titration technique. Both copper(III) and bismuth(V) were allowed to react with an excess of copper(I) and the excess of copper(I) was then back-titrated by an anodic oxidation. Bismuth(V) was determined alone by taking advantage of the reaction with manganese(II). In the Bi-Sr-Ca-Cu-O sample having a high transition temperature (T_c) of 90 K, the average valencies of copper and bismuth were found to be 2.144 and 3.119, respectively, using these techniques.