Preparation and characterization of Ce1−xGdxO2−δ (x = 0.1–0.3) as solid electrolyte for intermediate temperature SOFC

• Gd doped CeO2 was successfully synthesized by carbonate co-precipitation method.
• Lattice parameters and unit cell volume increases with increase in Gd concentration.
• The optical absorption spectra of GDC20 exhibits a red shift when compare to pure CeO2.
• Total conductivity of GDC10 and GDC20 is almost same between 473 K and 623 K.

The effect of Gd doping on the ionic conductivity of CeO2 for its use as a solid electrolyte material for the intermediate temperature solid oxide fuel cells (IT-SOFCs) has been explored here. Ce1−xGdxO2−δ (x = 0.1–0.3) samples are successfully synthesized by carbonate co-precipitation method. XRD, FT-IR, Raman spectroscopy, UV–Vis spectroscopy, SEM and impedance spectroscopy are used for structural and electrical characterization. From the XRD patterns, well-crystallite cubic fluorite structured solid solution is confirmed. As Gd3+ ions are doped into CeO2 lattice, the absorption spectrum exhibits a red shift when compared to CeO2. Raman spectra show a peaks at 463 cm−1, 546 and 600 cm−1, which are the characteristic peaks of doped ceria. Based on ac-impedance data, the total ionic conductivity is same for both Ce0.9Gd0.1O2–δ (GDC10) and Ce0.8Gd0.2O2–δ (GDC20) in the temperature range 473 K–623 K. Hence for Gd doped ceria solutions 10% and 20% of Gd, are proper doping level which leads to the maximum total conductivity. Above this doping level, the mobility of oxygen ions decreases the total conductivity due to blocking effect.