PREPARATION AND CHARACTERIZATION OF COPRECIPITATES AND MECHANICAL MIXTURES OF CALCIUM-STRONTIUM OXALATES USING XRD, SEM-EDX AND TG

In view of the study of the chemistry of the oxalate coprecipitation p rocess for preparing BiSrCaCuO superconductors, the characteristics of oxalates of calcium and strontium in the Ca(NO3)(2)-Sr(NO3)(2)-HNO3-H 2O-(NH4)(2)C2O4 system are investigated. Based on XRD, SEM and TG a co mparison between the crystal structure, morphology and thermal decompo sition behavior of coprecipitated and physically mixed calcium and str ontium oxalates with the same Ca/Sr stoichiometry is made. It is shown that the coprecipitated powders form homogeneous solid solutions of w hich the crystal structure, morphology and thermal behaviour depend on the Ca/Sr stoichiometry. (C) 1998 Elsevier Science B.V.