Carbon Species and Precise Elemental Analysis of Precursors for Superconducting (Bi,Pb)2Sr2Ca2Cu3Ox Tapes

 The chemical composition of BiPbSrCaCuO precursors prepared by different syntheses has to be checked analytically before further application to production of superconducting (Bi,Pb)2Sr2Ca2Cu3Ox tapes. Carbon species in concentrations below 0,1%(w/w) were observed to be possibly a source of gas evolving reactions during the heat treatment procedures for the superconducting phase formation. A method that allows the temperature controlled detection of CO2 resulting from reactions of various carbon species was developed based on an commercial C/H2O-analyser with IR gas detectors. By means of this method it is possible to relate the carbon content to the conditions of synthesis and technological steps of the tape production. The phase formation mechanism of the superconducting (Bi,Pb)2223 phase from a multiphase precursor strongly depends on its elemental composition. Titrimetric and ICP spectrometric methods that allow the determination of the content of the main components Bi, Pb, Ca, Sr, and Cu with high precision and accuracy were developed and their results were compared. The best results were obtained with a combined chemical-spectrometric procedure. The relative standard deviations (RSD) for all metallic elements do not exceed 1%. The analytical results of the main components and specific trace determinations are essential for the functioning of superconducting tapes.