Ionic conductivities of Na2Ti3O7, K2Ti4O9 and their related materials

Ionic conductivities were measured on the polycrystalline samples of layered titanates, Na₂Ti₃O₇ and K₂Ti₄O₉, and their derivatives. The activation energies and the prefactors of the conductions were 0.70 eV and 7.9 × 10 (Ωcm)^?1K for Na₂Ti₃O₇ and 0.81 eB and 1.1 × 10³ (Ωcm)^?1K for K₂Ti₄O₉. A small amount of Nb₂O₅ was doped to these titanates substituting TiO₂. Remarkable enhancements of ionic conductivities were observed with the doping. A new metastable phase, Li₂Ti₃O₇, was prepared by ion-exchange of Na₂Ti₃O₇ and its ionic conductivity was measured.