Titrimetric determination of the stoichiometric composition of ceramic high-temperature superconducting materials

To characterize the real stoichiometry of ceramic high-temperature superconductors of the Y-Ba-Cu-O type and the Bi(Pb)-Ca-Sr-Cu-O type complex, chemical methods including digestion, separation and subsequent titrimetric determination of the elemental components were investigated. Using optimized automatic titration procedures with photometric, potentiometric or voltametric equivalence point detection, a high accuracy of the analytical results could be achieved. The random as well as the systematic errors are less than 0.5%. The exact stoichiometric coefficients of the components and thereby the phase compositions or the single phase character of the materials were determined and compared with the results of X-ray diffraction measurements.