Effect of Sm and Gd dopants on structural characteristics and ionic conductivity of ceria

Sm- and Gd-doped ceria electrolytes Ce0.9Gd0.1O1.95 (GDC) and Ce0.9Sm0.1O1.95 (SDC) were prepared by using the Pechini method. The microstructural and physical properties of the samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry/differential thermal analysis (TG/DTA) and Fourier Transform Infrared Spectroscopy (FTIR). The TG/DTA and XRD results indicated that a single-phase fluorite structure formed at a relatively low calcination temperature, 400 °C. The XRD patterns of the samples revealed that the crystallization of the SDC powders was superior than that of the GDC powders at 400 °C. The sintering behavior and ionic conductivity of the GDC and SDC pellets were also investigated. The sintering results showed that the SDC samples were found to have higher sinterability than the GDC samples at a relatively low sintering temperature, 1300 °C, a significantly lower temperature than 1650 °C, which is required for ceria solid electrolytes prepared by solid state techniques. The impedance spectroscopy results revealed that SDC has a higher ionic conductivity compared to GDC.