Phase equilibria modelling in Bi-Sr-Co-O system-Towards crystal growth and melt-assisted material processing

In this contribution, high-temperature phase equilibria of the partly open Bi-Sr-Co-(O) system with oxygen content given by its activity in the surrounding atmosphere, were modelled based on the experimental phase diagram determined previously. For the assessment, we also used the previously reported thermodynamic data and phase equilibria for the quasibinary Bi-Co-(O), Sr-Co-(O) and Bi-Sr-(O) subsystems as well as the thermodynamic data of quaternary phases obtained from calorimetry and simultaneous thermal analysis. Namely, the oxide melt was described based on the Redlich-Kister parameters of the corresponding quasibinary systems and the solid oxides were considered as stoichiometric. Their heat capacity and entropy were determined from calorimetry and the enthalpy of formation was refined to reproduce their melting behaviour. The constructed phase diagram focused on solid-liquid equilibria is particularly important for designing the experiments of single crystal growth and melt assisted material processing of these highly significant cobaltites.