Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 73: Surface Dynamics: Reactions and Elementary Processes
O 73.1: Poster
Mittwoch, 9. März 2016, 18:15–20:30, Poster A
Near-ambient pressure XPS study of Pt-Ga alloys and their oxidation — •Mathias Grabau1, Sandra Krick Calderon1, Florian Rietzler1, Nicola Taccardi2, Peter Wasserscheid2, Florian Maier1, Hans-Peter Steinrück1, and Christian Papp1 — 1Physikalische Chemie 2, FAU Erlangen — 2Chemische Reaktionstechnik, FAU Erlangen
Alloys of 0.7 and 1.8 at.% Pt in Ga and their oxidation were probed by XPS. The Pt surface concentration of metallic alloys was determined as a function of temperature: A constant Pt concentration was observed at high temperature. Phase separation, that is, the formation of a solid Ga6Pt phase submerged in a Pt-depleted liquid phase, is indicated by a systematic decrease in Pt content at temperatures below 700 and 800 K, respectively. Exposure of the liquid-gas interface of such two-phase systems to oxygen at pressures between 3*10−7 and 1 mbar and at temperatures between 300 and 550 K led to the formation of Pt-enriched Ga2O3 films on the surface. Growth and composition of the formed films were examined in- and ex situ as a function of temperature and pressure. Within the examined parameter space, Pt concentration in the formed films is found to be independent of the bulk Pt concentration, growth and thickness of the films. This indicates defined solubility of Pt in Ga2O3 or the formation of discrete structural motives during oxidation.
We acknowledge the support of the Cluster of Excellence ’Engineering of Advanced Materials’.