Synthesis, structural and ionic conductivity of nanocrystalline Ce1−xLaxO2−δ as an electrolyte for IT-SOFC

Abstract La-doped CeO2 nanoparticles of composition Ce1−xLaxO2−δ (0 ≤ x ≤ 0.1) have been studied here as prospective electrolytes for intermediate temperature solid oxide fuel cell (IT-SOFC). They were synthesized by auto-combustion method and the powder samples were calcined at 700 oC to get ultrafine nanocrystalline particles. They were characterized by XRD, Raman, FTIR, XPS, DRS, FESEM/EDX, particle size analyzer and ac-impedance techniques. Ionic conductivity was measured from 350 − 750 oC. The Ce0.90La0.1O2−δ (0.1 LDC) and Ce0.95La0.05O2−δ (0.05 LDC) showed a maximum conductivity of 8.89 × 10−3 and 8.32× 10−3 S cm−1 at 700 oC, respectively. The σt of 0.1 LDC = 1.01× 10−2 S cm−1 at 750 oC. These values are higher than those reported for La-doped CeO2 in literature. The activation energy was found to be 0.70 eV and 0.87 eV, respectively. The SOFC performance with 0.05 LDC as electrolyte showed open circuit voltage of 0.81 V and maximum power density of 41 mW cm−2 at 650 oC using hydrogen as fuel.