The formation of the Ba(CuOx)(1-y)(CO3)(y) - A new phase in the Ba-Cu-C-O system: Thermal analysis results

Carbocuprate compounds are generally described Bs multiple perovskites with CO32- and Cu-O alternating layers containing Ba and/or Sr; they have gained an unexpected importance in the high temperature superconductivity field, because many compounds with transition temperature above 100 K belong to this class of materials. We have started a systematic study on phase formation and stabilisation in the Ba-Cu-C-O system in the temperature range 20-600 degrees C, by using thermal analysis techniques. Starting from a BaCO3-BaO2-CuO mixture (3:1:1 mol), a new phase isomorphic with BaCO3 formed after heat treatment above 390 degrees C in air. TG, DSC, EGA and high temperature XRD were employed to follow the complex interaction of the reactants with the atmosphere and the formation of the new phase.