Trivalent gallium ion conduction in NASICON-type solid

A new trivalent gallium (Ga3+) ion conducting solid was successfully developed by selecting the three dimensionally well-ordered NASICON-type structure. Although Ga is accepted as a species whose covalency is so high that trivalent Ga3+ ion is inappropriate ionic species in solids to migrate due to its strong bonding with surrounding ions such as oxide anion, we demonstrated the trivalent Ga3+ ion conduction in the NASICON-type (GaxTi1−x)4/(4−x)Nb(PO4)3 solids by strictly selecting the constituent cations. Among the samples prepared, (Ga0.1Ti0.9)40/39Nb(PO4)3 showed the highest Ga3+ ion conductivity of 5.1 × 10−5 S cm−1 at 600 °C.