Electrical properties of the (Y2 − xLix)Ti2O7 − x samples with LiO0.5 self-flux

• Co-existence of flux with YLT (Y2 − xLix)Ti2O7 − x, conductivity was not affected
• Addition of LiO0.5 as a flux in the YLT, preparation temperature was lowered
• For x = 0.070, which has the highest σ (total) and the lowest activation energy
• Ti atoms are in the mixed valence state.
• At 500 °C, no electronic conductivity is observed.

A series of (Y2 − xLix)Ti2O7 − x samples abbreviated as YLT-2L were prepared by the addition of 2x moles of LiO0.5 self-flux into the parent compound, where x = 0.040 to 0.110. Preparation temperatures were either 1300 or 1350 °C, depending on the amount of flux addition. However, the Y2Ti2O7 had no LiO0.5 co-existence; it was prepared at the highest temperature, 1600 °C. Relative densities of all the YLT-2L samples were larger than 97%, but for the Y2Ti2O7, it was 94.3(2)% only. By the addition of flux, preparation temperature reduced for more than 250 °C. Among all the YLT-2L samples, the one with x = 0.070 had the highest total electrical conductivity (2.90(2) × 10− 4 S·cm− 1 at 700 °C) and the lowest total activation energy (0.99(1) eV). By doping Li ion into the Y-site, oxygen vacancies were created, although YLT-2L samples had flux co-existence, electrical conductivity was still comparable to the parent compound reported by Yamaguchi et al. (1998) and Kobayashi et al. (2002). At 500, 600 and 700 °C, the ionic transference numbers (ti) found for the YLT-2L samples were 1.00(2), 0.96(2) and 0.90(3), respectively, and did not vary with the amount of substitution and the flux addition. Contribution of the electronic conductivity was due to the presence of a small amount of the Ti3 + ions in the samples investigated by the Ti K-edge XANES spectra.