| AVS 60th International Symposium and Exhibition | |
| Atom Probe Tomography Focus Topic | Wednesday Sessions |
| Session AP+AS+MI+NS+SS-WeA |
| Session: | APT and FIM Analysis of Catalysts and Nanoscale Materials |
| Presenter: | S.A. Thevuthasan, Pacific Northwest National Laboratory |
| Authors: | S.A. Thevuthasan, Pacific Northwest National Laboratory M.I. Nandasiri, Pacific Northwest National Laboratory A. Devaraj, Pacific Northwest National Laboratory D.E. Perea, Pacific Northwest National Laboratory T. Varga, Pacific Northwest National Laboratory V. Shutthanandan, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
There has been growing interest in developing materials which possess high oxygen ionic conduction at low temperatures for solid oxide fuel cell applications. In our group, we have been developing trivalent element doped creia/zirconia multilayer thin film structures for this purpose. We have grown (i) multilayers of high quality samaria doped ceria (SDC) and scandia stabilized zirconia (ScSZ) films, and (ii) samaria and gadolinia co-doped high quality ceria films using oxygen plasma-assisted molecular beam epitaxy (OPA-MBE). These films exhibit significantly higher oxygen ionic conduction at intermediate temperatures in comparison to bulk materials. Although we have demonstrated that these structures possess high oxygen ionic conduction at low and intermediate temperatures, we haven’t established the mechanisms associated with the enhancement in oxygen ionic conduction through these engineered heterogeneous interfaces.
Atom Probe Tomography (APT) can provide quantitative three-dimensional chemical analysis of materials with lateral and depth resolutions in the order of 0.2-0.3 nm and chemical sensitivity up to parts-per-million levels with field-of-view on the order of 100 × 100 × 100 nm3. Although APT has been extensively used to characterize metals, it is in its infancy in characterizing oxides and insulators. In addition, multilayer structure adds additional complications to the characterization of the doped ceria/zirconia multilayers. In this study, we have synthesized high quality SDC and ScSZ multilayers and used surface impedance spectroscopy to carry out detailed analysis of oxygen ionic conductivity as a function of individual layer thickness and dopant concentration. As a part of this study we attempted coupled scanning transmission electron microscopy and atom probe tomography to study the oxygen vacancy and dopant distributions along with the inter-diffusion and dopant segregation at the interfaces. These STEM/APT findings are correlated to the conductivity measurements and these results will be discussed.