Effect of doping concentration and sintering atmosphere on the microstructural and electrical characteristics of Y-doped SrTiO3 perovskite anode for SOFC

Abstract New materials for the anode of solid oxide fuel cells are needed, aiming at greater flexibility in the use of fuels and increased performance. Y-doped SrTiO3 (YST) has shown great potential for this application due to its mixed electrical (ionic and electronic) conductivity. In this work, undoped (ST) and doped samples with 4 mol.% (YST04) and 8 mol.% (YST08) of Y were sintered in argon (Ar) and Ar + 5% H2 to analyze the influence of doping and sintering atmosphere on the microstructural evolution and electrical properties. The atmosphere affects the doped sample, while the undoped samples are not affected since they present a low concentration of defects. Reducing atmosphere favored the electronic conduction phenomena, as it resulted in more round and homogeneous grains. However, the formation of a pyrochlore secondary phase in YST08 reduced the total electrical conductivity since it presents an insulating character. H2 presence increased the capacitance density considerably because it forms a structure with a higher concentration of interfaces between grains. Impedance values decreased with the insertion of dopant ion and with the presence of the reducing atmosphere agent during the sintering process.