Comparative study of fluorite-type ceria-based Ce1-x Ln (x) O2-delta (Ln = Tb, Gd, and Pr) mixed ionic electronic conductors densified at low temperatures

It has been reported that peak mixed conducting performance can only be obtained in doped ceria-based fluorite ceramics that contain cobalt sintering additives, when these materials are sintered below 1100 A degrees C. Hence, this article provides a comparative analysis of the electrochemical behavior of such materials formed under the aforementioned conditions. The transport properties of Ce0.8Tb0.2O2-delta (CTO), Ce0.8Gd0.2O2-delta (CGO), and Ce0.8Pr0.2O2-delta (CPO) with 2 mol% Co sintering aid were analyzed for samples prepared and sintered under similar conditions. The total conductivities of these samples were characterized by impedance spectroscopy under air atmosphere in the temperature range of 200-850 A degrees C. Oxide-ion transference numbers were determined by the modified electromotive force method under oxygen/air gradient. Ionic and electronic conductivities were calculated from transference numbers and total conductivity measurements and compared. CTO + Co and CPO + Co ceramic materials show higher relative contribution of the electronic transport compared to CGO + Co. Among these materials, CPO + Co shows the highest total and partial electronic conductivities, as well as the highest oxygen permeability, with essentially the same partial oxide-ion conduction as CGO + Co.