Synthesis and transport studies of one-dimensional ion conductors: AxGa4+XTi1−xO8 (A = Li, Na, K)

Ion exchange reactions of the sodium-ion conductor Na0.7Ga4.7Ti0.3O8 were investigated. Exposure to molten LiNO3 at 440 °C for 72 h resulted in a 2% decrease in the unit cell volume, whereas exposure to molten KNO3 under similar conditions had very little effect on the lattice parameters. The electrical conductivity of unexchanged Na0.7Ga4.7Ti0.3O8 ranged from ∼ 10− 7 S/cm at 300 °C to 10− 3 S/cm at 1000 °C with an activation energy of 0.75 eV. Ion exchange with LiNO3 resulted in an increase in conductivity whereas exchange with KNO3 resulted in a decrease. The differences in conductivity are attributed to differences in the size of the mobile cation.