1. Department of Materials Science Kiel University Kaiserstr. 2 24143 Kiel Germany
2. Laboratory for Gas Sensors IMTEK – Department of Microsystems Engineering University of Freiburg Georges-Koehler-Allee 102 79110 Freiburg Germany
3. Institute of Inorganic Chemistry Kiel University Max-Eyth-Str. 2 24118 Kiel Germany
4. Department of Thermal Energy Converters Fraunhofer Institute for Physical Measurement Techniques IPM Georges-Koehler-Allee 301 79110 Freiburg Germany