Effect of TiO₂ as an additive on the sintering performance of Sm-doped CeO₂-based electrolyte for solid oxide fuel...

In this work, TiO₂ was selected as an additive to the Sm_0.2Ce_0.8O_2-δ (SDC) electrolyte and its influence on the electrolyte properties were investigated. The tetrabutyl titanate hydrolysis product was introduced into the SDC samples as a source of TiO₂. The lattice contraction of SDC was observed by XRD when the smaller ionic radius Ti⁴⁺ (0.605Å) were substituted for Ce⁴⁺ (0.97 Å). XRD analysis shows that the doping content of the TiO₂ in SDC should be limited to 1 wt% to maintain the single-phase cubic fluorite structure of the SDC and avoid impurity phases. SEM characterizations suggest that the addition of TiO₂ significantly promoted the grain growth and the sintering activity, especially when doping with 0.5 wt% of TiO₂. The electrochemical measurements reveal that the addition of TiO₂ had little effect on the conductivity of SDC samples, which was 0.0306 S cm^-1 at 700°C. This study shows that 0.5 wt% TiO₂ doping can effectively improve the sintering activity without reducing the SDC performance.