Formation of continuous series of solid solutions in ternary and more component systems (reciprocal systems) without extremum in liduidus of binary systems, consist of metals, oxides, salts has been devoted to a considerable number of works. Solid solutions are solid two- or multicomponent homogeneous systems of variable composition (for example, type А xB1-x), in which atoms or ions of components, mixing in different ratios (0 <x <1), form a common crystal lattice, characteristic of one of components.