Empirical Electronic Polarizabilities: Deviations from the Additivity Rule. II. Structures Exhibiting Ion Conductivity

Ion conductivity in minerals and compounds is associated with continuous migration paths and leads to negative total electronic polarizability deviations [Δ = (αobs−αcalc)/αobs)] up to 13%. Such deviations can be related to continuous migration paths determined in an earlier Voronoi–Dirichlet Partition (VDP) analysis of fast‐ion conductors, that is, compounds such as LiB3O5 with 1D conductivity, Li4SiO4 with 2D conductivity, and Li2SO4 with 3D conductivity. Using the Voronoi–Dirichlet (VD) method in this study, the migration paths and the dimensionality of many more compounds with negative polarizability deviations are identified. Continuous migration paths are found for the confirmed Li‐ion conductors LiFePO4 and Li3VO4 and for the potential Li‐ion conductors LiGeBO4, CsLiB6O10, Li2Ti3O7, LiMn0.8Fe0.17PO4, Li2NaPO4, and LiNaSO4. Similarly, continuous migration paths are found for the confirmed Na‐ion conductors Na4P2O7, Na2SO4, and Na6Mg(SO4)4, and for the potential Na‐ion conductors Na6Mg2(CO3)4SO4, Na2TiSiO5, NaPO3, Na3SO4F, Na6(SO4)2FCl, Na15(SO4)5F4Cl, Na21(SO4)7F6Cl, Na22K(CO3)2(SO4)9Cl, and Na2SeO4. Potassium migration paths are found for the confirmed ion conductors KVO3 and K2SO4. In contrast to the application of VD partitioning of cation conductors, VD partitioning of anion conductors leads to migration paths in (Zr,Y)O8 polyhedra in Zr0.894Y0.095Hf0.011O1.95 and (Gd,Hf)O6 and (Gd,Hf)O8 polyhedra in Gd2Hf2O7 where O2− ions are mobile. This work represents a new approach to identify possible ion conductors by deviations between the total polarizabilities calculated from the sum of individual electronic polarizabilities of ions and the observed polarizabilities derived from refractive indices. The approach is verified by Voronoi Dirichlet Partition (VDP) analyses revealing the migration paths of mobile ions.