Triple-doped Ceria–Carbonate (Ce0.82La0.06Sm0.06Gd0.06O2-δ – (Li–Na)2CO3) nanocomposite solid electrolyte materials for LT–SOFC applications

Abstract

The Ce0.82La0.06Sm0.06Gd0.06O2-δ triple-doped ceria (LSG) and triple-doped ceria–carbonate nanocomposites (Ce0.82La0.06Sm0.06Gd0.06O2-δ – (Li–Na)2CO3) (LSG–LN) were prepared through sol-gel auto-combustion technique and followed by solid state mixing methods. The characterization of prepared triple-doped ceria (LSG) and triple-doped ceria–carbonate nanocomposites (LSG–LN) (such as LSG, 85LSG–15LN, 75LSG–25LN, and 65LSG–35LN, respectively) was carried out by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, impedance spectroscopy (IS), and the thermal expansion analyses. Sample formation, phase identification, surface morphologies and presence of elements in the prepared materials were analyzed with the help of XRD, SEM and EDS studies. The presence of oxygen vacancies and further structural analysis were investigated by the micro Raman spectroscopy. Total-ionic-conductivity and activation energies in the temperature range from 250 to 600 °C were evaluated from the IS measurements. Thermal expansion analysis revealed the moderate values of coefficients of expansion in all the samples. Triple-doping with carbonate phase resulted in highest total-ion-conductivities i.e., 4.2 × 10−1 S/cm and 4 × 10−1 S/cm for 65LSG–35LN and 75LSG–25LN, respectively. Total-ion-conductivities of the triple-doped ceria–carbonate nanocomposite materials were found to be high when compared to the triple-doped ceria (i.e., 3.8 × 10−2 S/cm). Therefore, it is concluded that these triple-doped ceria–carbonate nanocomposite materials will be useful as a promising electrolyte in low temperature solid oxide fuel cell (LT–SOFC) applications.