Electrical, thermal and catalytic properties of CeO2-Sm0.5Ti0.5O1.75 ceramics

The electrical conductivity of the ceramic composite, (CeO2)1−x(Sm0.5Ti0.5O1.75)x, where 0 ≤ x ≤ 0.2 has been investigated in air and in forming gas (8% H2 + 92% Ar). Complex impedance measurements indicated that the pyrochlore phase affected the grain-boundary conduction in these ceramic composites. The grain-boundary resistance decreased with increasing dopant content. The thermal behavior of these ceramics under reducing conditions was also investigated. Evaluations of catalytic behaviour showed that the addition of 5 mol% of pyrochlore phase to ceria improved the catalytic activity for steam reforming of methane.