Fig. 6: Chemical potential overlap as a descriptor for phase stability and synthesizability in rock salt high-entropy oxides.
a Chemical potential diagrams for Mg-O, Cu-O and Mn-O extracted from the Materials Project database, demonstrating stability windows of each cation in their AxOy binary oxides. A green color denotes oxygen chemical potential regions in which A2+O2− compositions are stable. Note the significant overlap MgO has with CuO and MnO, but the separation between CuO and MnO. b Chemical potential overlap descriptor (μoverlap) for all two-cation AO combinations. Cu, Mn, and Fe consistently have the smallest μoverlap with negative values corresponding to large separation, while Mg and Zn have the largest positive overlap. c Introducing chemical potential overlap as a third descriptor (color overlay) along with ΔHmix and σbonds reveals the uniqueness of prototypical MgCoNiCuZnO as the only 5- or 6-cation combination with significant overlap in A2+O2- binary oxide stability windows. This diagram also demonstrates the difficulty of stabilizing compositions with Cu, Mn and Fe. The combinations are colored with the same scale in part (b). Source data for (b) and (c) are provided as a Source Data file.
