SEQUENCE OF PHASE FORMATION DURING SOLID-STATE SYNTHESIS IN THE Y2O3-BAO-CUO SYSTEM

The sequence of formation of phases in the solid state synthesis of the YBa2Cu307-, Y2BaCuO5, BaCuO2, Y2Cu2O5 was studied using the methods of annealing, quenching, DTA, XRD and crystallooptical analysis in air in the range of temperatures 550-1100-degrees. The starting mixtures consisted of Y2O3, CuO, a Ba component introduced as a carbonate, peroxide or nitrate. It was established that the formation of ternary compounds in the system proceeds as a multiple-step reaction involving intermediate phases and is determined by the nature of the Ba containing component. The phase formation in the Y2O3-BaO-CuO system is described by several chemical reactions.