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)(2)Ti2O7 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 degreesC, respectively. A single phase of (La0.9Sr0.1)(2)Ti2O7 was also obtained by firing at 1000 degreesC 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 degreesC showed an ionic conductivity of 3.4 x 10(-6) S/cm at 700 degreesC, 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)(2)Ti2O7 was less than that of La2Ti2O7. (C) 2002 Elsevier Science B.V. All rights reserved.