Structural properties of Ce-doped strontium titanate for fuel cell applications

Abstract

Donor-doped strontium titanate represents an interesting class of materials for novel applications in solid oxide fuel cells. We have prepared three different stoichiometries, Sr_1−xCe_xTiO_3±δ, Sr_1−1.5xCe_xTiO_3±δ and Sr_1−2xCe_xTiO_3±δ (0.05< x <0.15) to examine structural properties when prepared in air. We have found that no matter what the starting stoichiometry, Sr_1−1.5xCe_xTiO_3±δ would always preferentially form. This agrees with the current defect model for donor-doped strontium titanate. When examined using X-ray diffraction the samples appeared to be cubic, however, using neutron diffraction we found there was a slight distortion of the perovskite structure. From our results it would appear this distortion was tetragonal but the resolution of our data does not allow us to conclusively differentiate this from the closely related rhombohedral symmetry.