TY - THES A1 - Kühn, Julius T1 - Composition and chemistry of Pd-Ni-Co thin film alloys for hydrogen related applications N2 - The discovery and design of high performance Pd-alloys is of great interest for the use of hydrogen as a future energy carrier. Therefore hydrogen has to be detected, separated from other gases and stored. In this respect this thesis presents the combinatorial synthesis and characterization of the ternary Pd-Ni-Co alloy System over a wide composition range based on so-called thin film alloy libraries. Those libraries are model systems to characterize a large number of alloy compositions at the same time. The sputter-deposition process is optimized for the gradient of the Pd concentration on the surface of the alloy library by the use of electron-excited Auger electron spectroscopy. The scientific goal of this work is the experimental Investigation of adsorbate-induced surface segregation phenomena on alloy libraries. The surface and bulk compositions of an alloy library are studied after deposition, H2 exposure and H2S poisoning. The co-segregation of Ni and Co to the surface is observed. The segregation process is influenced by the oxidation of Ni and Co due to the contact with ambient air, by H2 and by H2S poisoning. Also at very high Pd concentrations in the range of 87 at.% to 97 at.%, which is interesting for the detection of very low H2-Concentrations in air, the co-segregation of Ni and Co takes place. The poisoning effects were investigated in detail on a pre-selected Pd-Ni-Co alloy by photoelectron spectroscopy (XPS, HAXPES) in addition to AES and EDX. The composition profile of the alloy on the nm scale is acquired and the surface and bulk chemistry is discussed before and after poisoning. The composition of the alloy only changed within the first 3 nm due to H2S exposure. In the ternary Pd-Ni-Co alloy system Pd is present in its metallic state, while Ni and Co show several oxidation states. The presented concepts of ternary alloy development pave the way for the systematic synthesis and characterization of new ternary transition metal alloy systems. KW - Hydrogen sensor KW - Library of ternary Pd-alloys KW - AES KW - (HAX)PES KW - REM/EDX KW - Wasserstoffsensor KW - Bibliothek ternärer Pd-Legierungen PY - 2016 DO - https://doi.org/10.14279/depositonce-5002 SP - 1 EP - 127 PB - Technische Universität CY - Berlin AN - OPUS4-35680 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -