Comparative study of samarium-doped ceria nanopowders synthesized by various chemical synthesis routes

Abstract This article presents various chemical synthesis techniques to form samarium-doped ceria (SDC) nanopowders that can be used as electrolyte materials for fabricating solid oxide fuel cells (SOFC). Ce0.8Sm0.2O2-δ powders were prepared by three chemical synthesis routes: glycine nitrate precursor combustion, co-precipitation and sol-gel. SDC pellets were formed using uniaxial and isostatic pressing approaches and sintered at 1200 °C for 5 h. Crystal and thermal features, chemical functional groups were investigated by X-ray diffraction (XRD), combined thermogravimetric and differential thermal analysis (TG/DTA) and Fourier transform infrared (FT-IR) analysis methods. It is shown that the crystallization of the samples synthesized by combustion method starts at the comparably low calcination temperature (171.42 °C) as compared to the samples obtained by sol-gel and co-precipitation methods (391.94 °C and 368.05 °C respectively). The structural and morphological properties of all the samples were analysed via Scanning (SEM) and Transmission (TEM) electron microscopies that have shown very dense structures with no intergranular pores. Impedance (IS) spectroscopy analysis shows three types of processes, which appeared in the structures that include grain, grain boundary, and response from platinum electrodes. The obtained results show that the pellet synthesized by combustion synthesis route has higher total conductivity value 3.04∙10−2 S∙cm−1at 800 °C and the lowest activation energy comparing to co-precipitation and sol-gel.