Effect of Ta-doping on the ionic conductivity of lithium titanate

The powders of Li2Ti1−xTaxO3+x/2 (0.10 ≤ x ≤ 0.35) were synthesized by a solid-state reaction method and Li2Ti1−xTaxO3+x/2 sintered bodies were fabricated with the powders at 1100 °C for 6 h. Phase analysis and microstructure of the samples were determined by XRD and SEM, respectively. Complex electrochemical impedance spectroscopy was used to evaluate the electrical conduction properties of the sintered ceramics. The experimental results showed that Ta2O5 could dissolve in Li2TiO3 and reached the saturation degree of about 25% at 1100 °C. The doped samples possessed much higher ionic conductivity than the primitive Li2TiO3 with the most favorable doping level of 25%. At 300 °C, the ionic conductivity of the doped Li2Ti0.75Ta0.25O3.125 (x = 0.25) ceramics achieved 9.00 × 10−5 S cm−1, more than 2 orders of magnitude higher than that of the primitive Li2TiO3 ceramics (7.75 × 10−7 S cm−1).