The isotope exchange depth profiling (IEDP) technique using SIMS and LEIS

The determination of the mass transport kinetics of oxide materials for use in electrochemical systems such as fuel cells, sensors and oxygen separators is a significant challenge. Several techniques have been proposed to derive these data experimentally with only the oxygen isotope exchange depth profile technique coupled with secondary ion mass spectrometry (SIMS) providing a direct measure of these kinetic parameters. Whilst this allows kinetic information to be obtained, there is a lack of knowledge of the surface chemistry of these complex processes. The advent of low-energy ion scattering (LEIS) now offers the opportunity of correlating exchange kinetics with chemical processes at materials atomic surfaces, giving unprecedented levels of information on electrochemical systems with isotopic discrimination. Here, the challenges of these techniques, including sample preparation, are discussed and the advantages of the combined approach of SIMS and LEIS illustrated with reference to key literature data