The formation regions of solid solutions with the structure gamma-KFeO
2 and co-cationic conductivity in the systems (K, Rb, Cs)MO(2)-TiO2 (M
= Ga, Fe) are studied. Single-phase regions of gamma-solid solutions
are found to expand with the growing cation size of the rigid lattice.
The introduction of a third alkali cation is shown to enhance the pol
yalkaline effect observed earlier for similar electrolytes with two al
kali ions.