Phase relations in alkaline earth-manganese-oxygen systems: Equilibrium and metastable states

Abstract

This paper presents a systematic review of the literature concerned with the physicochemical analysis of the thermodynamic systems Ca-Mn-O, Sr-Mn-O, and Ba-Mn-O at variable temperature and oxygen pressure in the gas phase. Available data are systematized in the form of projections of the phase diagrams of these systems onto the alkaline earth-managanese-oxygen composition triangles. Compatibility triangles are identified in the projections, and the phase relations involved are discussed. The conclusion is drawn that the physicochemical data reported to date are insufficient for the thermodynamic analysis of heterogeneous equilibria in the A-Mn-O systems, which is hindered primarily by the lack of information about the equilibrium oxygen pressure as a function of temperature for the thermal dissociation (or oxidation) of AxMnyOz (A = Ca, Sr, Ba) oxides.