Synthesis and Characterization of (Gd, Nd)‐Doped CeO 2 /SrTiO 3 Heterostructures for IT‐SOFC

ABSTRACT The present investigation evaluates the usability of Gd and Nd co‐doped CeO 2 (0.05Gd 0.05Nd) and CeO 2 (0.05Gd 0.05Nd) + SrTiO 3 (60:40) composite synthesized by glycine combustion as electrolytes in medium‐temperature solid oxide fuel cells (SOFCs) through a comprehensive analysis of their ionic conductivity and structural characteristics. The crystal structure and phase analyses of the materials were characterized by x‐ray diffraction (XRD), and it was confirmed that both samples successfully formed the targeted cubic fluorite (CeO 2 ) and perovskite (SrTiO 3 ) phases, and the dopant elements were integrated into the main lattice. Raman spectroscopy was used to study the effect of doping elements on the lattice dynamics and oxygen vacancies. FESEM (field emission scanning electron microscopy) analyses demonstrated that the addition of SrTiO 3 reduced the grain size from 90.45 to 33.39 nm, leading to a more homogeneous and compact microstructure. Conductivity and activation energy were assessed using electrochemical impedance spectroscopy within the temperature range of 400–550°C. In this study, it was observed that the total conductivity values of the prepared materials measured under air atmosphere are higher than the typical values reported in the literature for SOFC electrolytes. This suggests that the conduction cannot be explained solely by oxygen ion transport and may indicate the presence of a possible mixed conduction mechanism in which both ionic and electronic charge carriers are involved. In this context, the obtained findings indicate that the studied system may be considered a potential candidate as a mixed‐conducting electrode material for intermediate‐temperature SOFCs.