Effect of La3+ and Pr3+ co-doping on structural, thermal and electrical properties of ceria ceramics as solid electrolytes for IT-SOFC applications

In the present investigation, the effect of La3+ and Pr3+ co-doping on structural, thermal and electrical properties of ceria ceramics useful as solid electrolytes in intermediate temperature solid oxide fuel cells (IT-SOFCs) has been studied. The co-doped ceria Ce0.8Pr0.2-xLaxO2-δ samples have been prepared successfully via sol-gel auto-combustion synthesis. The high dense ceramic samples have been achieved by carry out an optimized conventional sintering at 1300 °C for 4 h. The powder X-ray diffraction analysis of all the co-doped ceria ceramics revealed the single phase with cubic-fluorite structure formation. Crystallographic information has been carried out from the powder X-ray diffraction and Rietveld refinement analysis. The scanning electron microscope and energy dispersive spectroscopy analysis revealed the smaller grain size with high density in microstructure and stoichiometric elemental confirmations. Raman spectra of prepared ceramics revealed the information of phase and oxygen vacancy formation in the entire compositions. The dilatometric studies of prepared co-doped ceria ceramics revealed the moderate coefficients of thermal expansion. The electrical parameters such as total conductivities and activation energies have been studied with the help of impedance spectroscopy. Among all these co-doped ceria ceramic samples, Ce0.80Pr0.10La0.10O2−δ found to exhibit the highest value of total ionic conductivity with minimum activation energy and this makes it could be a promising electrolyte material for IT-SOFC applications.