Electrical conductivity of layered compounds in SrO–La2O3–TiO2 systems prepared by the Pechini process

The electrical conductivity of layered-perovskite-type La2Ti2O7 and Sr-doped La2Ti2O7 has been studied. La2Ti2O7 and (La0.9Sr0.1)2Ti2O7 with a layered-perovskite structure were successfully prepared by the Pechini process. The grain size of La2Ti2O7 was found to be 41, 57, and 70 nm for a firing temperature of 700, 1000, and 1300 °C, respectively. A single phase of (La0.9Sr0.1)2Ti2O7 was also obtained by firing at 1000 °C for only 2 h. The electrical conductivity of the layered compounds was measured as a function of partial oxygen pressures and temperatures by a complex impedance technique. La2Ti2O7 fired at 700 °C showed an ionic conductivity of 3.4×10−6 S/cm at 700 °C, due to the Frenkel defects incorporated by low-temperature synthesis. As a result of the grain size refinement, the enhancement of electronic conductivity was also observed for La2Ti2O7. The ionic conductivity of (La0.9Sr0.1)2Ti2O7 was less than that of La2Ti2O7.