Self-propagating room temperature synthesis of Ce0.8SmXM0.2-xO1.9(M= Gd, Nd, 0≤x≤0.2) co-doped ceria oxide-ion conductor ceramics for solid oxide fuel cells

Abstract

Ce0.8SmXM0.2-xO1.9 (M = Gd, Nd, 0≤x ≤ 0.2) co-doped cerium oxide ionic conductor ceramics are prepared for the first time by a simple and time-saving self-propagating room temperature (SPRT) method. The uncalcined ceramic powders and the microstructure of the pellets sintered at 1400 °C are characterized by thermogravimetric analysis, Fourier-transformed infrared spectroscopy, scanning electron microscopy, and X-ray diffractometry. The density of the pellets is determined using the Archimedes method. The oxygen ion conductivity properties of the electrolytes are measured by electrochemical impedance spectroscopy. Impurity-free, non-porous electrolytes with high-density (>95 %) are successfully prepared. We report that the influence of dopant type and composition on the physical properties of the electrolytes prepared by the SPRT method is insignificant, with the total dopant concentration kept constant at 20 %. The dopant type and composition mainly influence the lattice parameters, grain interior conductivity of the grains, and the activation energy of the internal conductivity of the grains. Maximum oxygen ion conductivities are demonstrated with Ce0.8Sm0.1Nd0.1O1.9 and Ce0.8Sm0.15Gd0.05O1.9 samples for the Nd and Gd series, respectively. The highest ionic conductivity of 0.0677 S cm−1 and the lowest activation energy of 0.75 eV is achieved at a value of 10%Nd-10%Sm.