Electrolyte materials were sought that exhibited enhanced conductivity at 773 to 1073K. Sm-doped ceria was considered to be a promising candidate due to its high oxygen ion conductivity. A theoretical investigation using first-principles and kinetic lattice Monte Carlo computation was used to highlight the trends in oxygen ion conductivity as a function of dopant content and temperature in Sm-doped ceria. Using first-principles calculations, oxygen vacancy formation and migration were examined at first, second, and third nearest neighbor positions to a Sm ion. The activation energies for oxygen vacancy migration along various pathways in Sm-doped ceria computed using first-principles were used as input to the kinetic lattice Monte Carlo model to study vacancy mediated diffusion. Sm-doped ceria with 20% mole fraction of dopant content yielded the maximum conductivity, which was in very good agreement with experimentally identified compositions. Rationale for increase in conductivity as a function of increase in dopant content and subsequent decrease in conductivity at higher dopant fractions in Sm-doped ceria was presented. This combined methodology of first-principles and kinetic lattice Monte Carlo computation was a useful tool for the design and identification of various ceria-based electrolyte materials.

A Blend of First-Principles and Kinetic Lattice Monte Carlo Computation to Optimize Samarium-Doped Ceria. P.P.Dholabhai, J.B.Adams: Journal of Materials Science, 2012, 47[21], 7530-41