Bi based 2223 superconducting materials prepared by the "glassy-matrix" precursor method influence of the nature of the additional crystalline precursor

Different types of precursors (SrCaCuO3, SrCaCu2O4, SrCuO2 and Ca0.9Sr0.1CuO2) are used in order to produce a 2223 material as pure as possible by the glassy-matrix method. Depending on the initial mixture for the expected stoichiometry, i.e. 2223 or 2234, the composition of the glassy matrix was found to contain different concentrations in calcium and copper ions. When the glassy phase contained strontium, 2201 or 2212 related phases were produced by recrystallization of the glassy matrix leading to "static systems" whereas when calcium and copper "free ions" were produced in situ, 2223 phase formation was enhanced. This is discussed as due to the presence of Ca4Bi6O13 as an intermediate phase. In conclusion, SrCuO2 is thus probably the best precursor for the formation of the 2223 phase.