Phase Relations in a NaFeO(2)-SnO(2) (0–50 mol.% SnO(2)) System and the Crystal Structure and Conductivity of Na(0.8)Fe(0.8)Sn(0.2)O(2)

With the view of developing new materials for sodium and sodium-ion power sources, NaFeO(2)-SnO(2) (0–50 mol.% SnO(2)) powders were synthesized using a solid state method, and their phase composition and crystal structure were studied. A phase of the Na(0.8)Fe(0.8)Sn(0.2)O(2) composition with a layered rhombohedral structure of the α-NaFeO(2) type was found when the tin dioxide content was 20 mol.%. The phase produced was of an O3 structural type. O3-type phases have sufficiently good performance when used as cathode materials in sodium-ion batteries and, moreover, often have a rather high sodium-cation conductivity. A two-dimensional migration map was built using Voronoi–Dirichlet partition and TOPOS software package. The sodium-ion conductivity of Na(0.8)Fe(0.8)Sn(0.2)O(2) at room temperature was rated low (10(−8) S × cm(−1) at 20 °C), which may be the result of channels too narrow for Na(+) migration. The results obtained show that the application of the compound studied in this work as a solid electrolyte in sodium power sources is unlikely. It is the potential use of Na(0.8)Fe(0.8)Sn(0.2)O(2) as the active material of cathodes in Na and Na-ion power sources that presents practical interest.