Conductivity and expansion at high temperature in Sr0.7La0.3TiO3-α prepared under reducing atmosphere

Sr0.7La0.3TiO3-alpha specimens were prepared in reducing atmosphere, and the structural and electrical properties were studied. The lattice parameter of Sr0.7La0.3TiO3-alpha at room temperature was larger than that expected from Vegard's law between SrTiO3 and LaTiO3 due to the reductive expansion. The conductivity of this specimen was 100 S cm(-1) 1000 degrees C, p(O2) = 10(-1) Pa. However, the conductivity was not preserved after an oxidation-reduction cycle. Over p(O2) = 10(2) Pa, the conductivity drastically dropped with increasing p(O2). The thermal expansion coefficient of Sr0.7La0.3TiO3-alpha was 11.8 x 10(-6) K-1 in 9% H-2/N-2 (room temperature - 1000 degrees C). In this Sr0.7La0.3TiO3-alpha, the chemical expansion on oxidation reached Delta l/l(o) = 0.51%, when changing p(O2) from 10(-1) Pa to 2 x 10(4) Pa (air) at 1000 degrees C.