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 supercond uctivity field, because many compounds with transition temperature abo ve 100 K belong to this class of materials. We have started a systemat ic 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 t echniques. Starting from a BaCO3-BaO2-CuO mixture (3:1:1 mol), a new p hase isomorphic with BaCO3 formed after heat treatment above 390 degre es C in air. TG, DSC, EGA and high temperature XRD were employed to fo llow the complex interaction of the reactants with the atmosphere and the formation of the new phase.