Thermal Expansion Properties of Sr1-xLaxTiO3-δ ((0 {less than or equal to} x {less than or equal to} 0.3) Perovskites in Solid Oxide Fuel Cells

Abstract

Sr1-xLaxTiO3-δ perovskites are strong candidates for use as the anode and interconnect materials in solid oxide fuel cells. The thermal expansion properties of these materials with La contents of 0 <= x <= 0.3 during oxidation-reduction (redox) cycling were investigated. The thermal expansion coefficients (TECs) in air increased with increasing La content. TECs in an H2 atmosphere showed an opposite trend. Shrinkage occurred in the reducing atmosphere, and no further shrinkages of the reduced samples were observed upon re-exposure to the same environment. On the other hand, the pre-reduced samples expanded in air. These thermal expansion properties are expected to be related to the release and absorption of oxygen as well as the disappearance of excess cation and oxygen vacancies in the perovskite structure.