1. Chair for MEMS Materials, Institute for Materials, Faculty of Mechanical Engineering, Ruhr University Bochum, Universitaetsstrasse 150, D-44801 Bochum, Germany
2. Institute of Materials Research, German Aerospace Center (DLR), Linder Hoehe, D-51147 Cologne, Germany
3. Institute for Inorganic and Analytical Chemistry, Justus-Liebig-University Gießen, Heinrich-Buff-Ring 17, D-35392 Gießen, Germany