Microscopic origin of high mobility of oxygen vacances in doped ceria

1. X19A Microscopic origin of high mobility of oxygen vacances in doped ceria Anna Kossoy, Anatoly I. Frenkel, Qi Wang, Ellen Wachtel, and Igor Lubomirsky Weizmann Institute of Science, Rehovot, Israel and Yeshiva University, New York • Cerium oxide, in both pure and doped forms, is one of the most important and extensively studied oxygen ion conductors. • Interactions between the cation and oxygen vacancies are thought to be directly responsible for a number of effects such as resistance to radiation damage, vacancy ordering leading to phase transformations, dependence of ionic conductivity on the ionic radius of the dopant, and the non-linear elastic effects. • Combination of powder x-ray diffraction and absorption spectroscopy data on the thin films of Gd doped ceria, allowed us to observe a new effect: the elongation of the Ce-oxygen vacancy distance relative to the average fluorite structure. • This effect helps explain enhanced oxygen vacancy mobility. • Our findings may have considerable practical importance for the rapidly developing field of microscopic fuel cells. Left: Fourier transform magnitudes of the LIII edge EXAFS spectra of Ce and Gd for powders and thin films of Ce0.8Gd0.2O1.9 with and without strain. Right: EXAFS-derived bond lengths for a) cation–anion and b) cation–cation pairs obtained for the coarse-grain powders and thin films of Ce0.8Gd0.2O1.9 with and without compressive strain A. Kossoy, A. I. Frenkel, Q. Wang, E. Wachtel, I. Lubomirsky Local structure and strain-induced distortion in Ce0.8Gd0.2O1.9Advanced Materials 22, 1659-1662 (2010) Work performed on beamlines X19A and X18B.