Dresden 2014 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 50: Oxide and Insulator Surfaces I
O 50.9: Vortrag
Mittwoch, 2. April 2014, 12:30–12:45, WIL A317
Structural, electronic and thermodynamic properties of YBaCo4O7+δ from DFT+U calculations — •Jakub Goclon and Bernd Meyer — Interdisciplinary Center for Molecular Materials and Computer-Chemistry-Center, FAU Erlangen-Nürnberg
In the past decade, one of the main goals in solid oxide fuel cell (SOFC) research was to develop intermediate-temperature SOFCs (IT-SOFCs) operating at 600–800 ∘C. Recently, a new family of layered cobalt oxide compounds based on the YBaCo4O7 structure has been proposed for application as cathode material in IT-SOFCs. The compounds are able to adsorb in a reversible way up to δ=1.5 oxygen atoms per unit formula, both at low and high temperatures.
We performed DFT+U calculations for different YBaCo4O7 bulk structures based on structural models proposed in the literature. We then focused on the bulk properties of the oxygen-rich phases after oxygen incorporation, searching for the most favorable positions of the additional oxygen atoms. In the second part of this work we determined the most stable termination (structure, chemical composition) of the YBaCo4O7(001) surface based on thermodynamic analysis. Analogical calculations were performed for oxygen adsorption on YBaCo4O8(001). The local electronic structure and the local distribution of the cobalt cations in close vicinity of the additional oxygen atoms has been carefully analyzed and will be discussed. In addition, results from corresponding calculations for the bulk and low-index surfaces of Co3O4 will be shown as reference.