Many studies have been devoted to solid high-entropy alloys and solutions, as their unique mechanical and physicochemical characteristics have been revealed. It is believed that the field of high-entropy solutions conventionally begins with five components. For example, Cantor's alloy is a solid solution based on the FCC lattice FeNiMnCrCo, which has remarkable properties . To synthesize a solid high-entropy alloy or a solid solution of oxides is quite a difficult task. In the molten state it is much easier to prepare a homogeneous true solution. In this case, obviously, it should be used in the liquid state.