Mechanical, Electrical, and Optical Properties of (Pr,Ce)O2 Solid Solutions: Kinetic Studies

Abstract

Praseodymium doped cerium oxide (PCO) shows mixed ionic and electronic conducting (MIEC) characteristics at relatively high pO2 (e.g. air) and enhanced oxygen storage capacity (OSC), of interest for solid oxide fuel cell (SOFC) cathodes and three way catalysts, resulting from the ready reduction of Pr to its trivalent state. This reduction also results in a change of lattice parameter, known as chemical expansion, and changes in optical absorption related to the formation of a Pr impurity band. These properties can be measured as a function of time, yielding oxide ion diffusion and surface exchange coefficients. In this manuscript, the diffusivity and/or surface exchange of PCO is explored using TGA and dilatometry of bulk specimens and HTXRD and optical absorption of thin films. The HTXRD and optical absorption measurements promise the ability to monitor both thermodynamic and kinetic properties of thin film materials exhibiting wide swings in oxygen stoichiometry.