Experimental Phase Equilibria in the Sr-Ca-Cu-O System Under Reduced Oxygen Atmosphere

Abstract

Phase equilibria were studied in the Sr-Ca-Cu-O system by annealing samples at 1153K in Ar-O₂ gas mixtures. The stability ranges of the oxide solid solutions were observed by X-ray diffraction measurements especially at 4 compositions in 12 gas mixtures. 4 sets of invariant 4-phase equilibrium and their oxygen partial pressure, P_O2, were deduced from the surrounding 3-phase equilibria. The compositions of the related phases were evaluated by combining EDX analysis and the sample compositions. These results are compared with equilibrium calculations based on thermodynamic modelling.