Ionic conductivity of infiltrated Ln (Ln = Gd, Sm, Y)-doped ceria

This work studies the ionic conductivity of nanosized Gd-, Sm-, and Y-doped ceria prepared by the infiltration/impregnation method. The nanoparticles were deposited onto porous pure ceria substrates via infiltration-heating processes, and the conductivity was determined with the electrochemical impedance spectroscopy (EIS) using the conductive model for infiltrated phases. The conductivity of the infiltrated doped ceria changes with the doping amount, and Gd_0.25Ce_0.75O_2−δ, Sm_0.2Ce_0.8O_2−δ, and Y_0.15Ce_0.85O_2−δ show the highest values of 2.56, 3.01, and 2.07 × 10⁻³ S·cm⁻¹ at 600 °C, respectively. Overall, Sm-doped samples show the highest conductivity, while Y-doped samples show the lowest conductivity. In consideration of the Bruggeman factor, the intrinsic conductivity of the infiltrated doped ceria was calculated. Compared with the bulk doped ceria, the intrinsic conductivity is higher while the activation energy is lower, which may suggest different conduction mechanisms. Besides, co-doping effects on the conductivity of the infiltrated sample are less obvious than those of the bulk sample.