Microstructure and electrical properties of SrTi0.98Nd0.02O3-δ -based composites applied as porous layers for SOFCs

SrTi0.98Nb0.02O3-δ-CeO2 and SrTi0.98Nb0.02O3-δ-YSZ composites have been prepared. In order to evaluate the applicability of the material for solid oxide fuel cells (SOFCs) both bulk samples and porous composite layers have been investigated. The electrical conductivity of the bulk samples was measured using the four-terminal DC method, whereas the conductivity of the porous layers was determined using the DC Van der Pauw method in the temperature range of 400–850 °C in humidified hydrogen. The microstructure of the samples was characterized by scanning electron microscopy (SEM) technique. From the fuel cells point of view a significant advantage of the bulk Sr(Ti,Nb)O3-δ-YSZ over Sr(Ti,Nb)O3-δ-CeO2 composite was noticed in the case of microstructure and electrical properties. Ceria grains in the Sr(Ti,Nb)O3-δ-CeO2 composite tend to form large clusters, especially at the grain boundaries. This phenomenon results in sample cracking during redox cycles.