Modified strontium titanates have received much attention recently for their potential as anode material in solid oxide fuel cells (SOFC). Their inherent redox stability and superior tolerance to sulphur poisoning and coking as compared to Ni based cermet anodes could improve durability of SOFC systems dramatically. Various substitution strategies can be deployed to optimise materials properties in these strontium titanates, such as electronic conductivity, electrocatalytic activity, chemical stability and sinterability, and thus mechanical strength. Substitution strategies not only cover choice and amount of substituent, but also perovskite defect chemistry, distinguishing between A-site deficiency (A_1−xBO₃) and cation-stoichiometry (ABO_3+δ). Literature suggests distinct differences in the materials properties between the latter two compositional approaches. After discussing the defect chemistry of modified strontium titanates, this paper reviews three different A-site deficient donor (La, Y, Nb) substituted strontium titanates for their electrical behaviour and fuel cell performance. Promising performances in both electrolyte as well as anode supported cell designs have been obtained, when using hydrogen as fuel. Performances are retained after numerous redox cycles. Long term stability in sulphur and carbon containing fuels still needs to be explored in greater detail.

The authors observed an extremely high permittivity ($\sim 35000$ at $T_C$ ) in barium zirconate titanate $\left(\mathrm{Ba}{\mathrm{Zr}}_{0.1}{\mathrm{Ti}}_{0.9}{\mathrm{O}}_3\right)$ ceramics with holmium substitution $(1–5\mathrm{mol}\%)$ in Ba site. Careful microstructural investigation and energy dispersive spectroscopy analysis of the $1–2\mathrm{mol}\%$ of Ho substituted ceramics showed the enrichment of a Ho-phase along the grain boundaries with a composition close to the ${\mathrm{Ho}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$ pyrochlore. The formation of Ho rich phase resulted in the Maxwell-Wagner polarization mechanism, which leads to this unusually high permittivity. Ceramics with $3\mathrm{mol}\%$ or higher Ho content showed lesser permittivity values compared to $1–2\mathrm{mol}\%$ , probably due to the increase in pyrochlore phase. These high dielectric constant ceramics are useful in nanoscale devices.

Metal supported solid oxide fuel cell (MSC) technology has a significant potential for mobile applications, due to high electrical efficiencies, fuel flexibility, cheap materials, and mechanical robustness. The MSC concept in the current study relies on scalable, ceramic processing methodology. Two MSC generations with different anodes, one with a FeCr-ScYSZ-based anode backbone and one with a FeCr-titanate based anode backbone, both infiltrated with GDC and Ni electro catalysts, were tested using methane containing fuel. It was found that the internal reforming activity of the anodes is reduced as compared to state-of-the-art Ni-cermet anodes, due to the lower Ni content in the anodes of the MSCs. Still, power densities of ca. 0.22 W cm ⁻² were obtained at 650 °C in a methane/steam fuel and long-term tests at medium to high fuel utilization were successfully demonstrated on the titanate based MSC.