Tetravalent Zr4+ ion conduction in NASICON-type phosphate solids

The ionic conduction of mono-, di-, and trivalent ions in solids is popular in solid state science and the next target ion species to migrate in solids are tetravalent ions. Here, a tetravalent cation conductor which shows high conductivity, comparable to the conductivity range of the representative divalent oxide anion conductors, was artificially designed by strictly selecting the constituent elements and the structure. The tetravalent ion conducting solid electrolyte proposed here shows considerable high ion conductivity and promising applications, such as in rechargeable batteries and chemical sensors for global environmental monitoring, are greatly expected.