Density Functional Theory calculations on microscopic aspects of oxygen diffusion in ceria-based materials

The critical role of the ionic conductivity properties of materials in the development of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) technology has been emphasized over the past decade. However, from a fundamental point of view, little is known of the physicochemical parameters influencing ionic diffusion in these conductors. We attempted, through a Density Functional Theory investigation, to develop a new approach for an oxygen diffusion study in solids at the atomic scale. This methodology relies on the evaluation and comparison of steric, energetic, and chemical bonding factors along with the consideration of charge transfers when mixed valences do exist. Microscopic aspects of oxygen diffusion in the ionic conductor ceria-based materials have been investigated by means of this procedure. It has been demonstrated that steric and polarizability effects prevail over other ones for both nonstoichiometric and doped ceria. (C) 2004 Wiley Periodicals, Inc.