Chair for Multicomponent Materials

Functional nanocomposites

Highly filled particulate nanocomposite films consisting of metal nanoparticles in a dielectric organic or ceramic matrix have unique functional properties with hosts of applications. While common wet chemical methods have severe limitations at high filling factors, vapor phase deposition techniques are ideal for tailoring the nanostructure and the resulting properties. Vapor phase deposition, inter alia, allows excellent control of the metallic filling factor and its depth profile as well as the incorporation of alloy nanoparticles with well-defined composition. Since the nanostructure forms by self-organization, the approach can be upscaled for large-area deposition. We apply various methods such as sputtering, evaporation, and plasma polymerization for the deposition of the matrix component, while the metallic components were mostly sputter-deposited or evaporated. Moreover, a high-rate gas aggregation cluster source is utilized to obtain independent control of filling factor and size of the embedded nanoparticles, which is crucial for applications based on the interaction of very small nanoparticles in close proximity where quantum effects come into play. Examples include optical composites with tuned particle surface plasmon resonances and tailored coupling of the plasmonic dipole oscillations. For plasmonic applications, magnetic high frequency materials with cut-off frequencies well above 1 GHz, sensors and photoswitchable devices that are based on the huge change in the electronic properties near the percolation threshold, and biocompatible antibacterial coatings with tailored release rate. In addition to the particulate composites, we also explore magnetoelectric layered composites consisting of magnetostrictive and piezoelectric layers as low frequency magnetic field sensors with sensitivities down to the pT range. Finally, we developed a new concept of a robust, fully integrable, broad band magnetic field sensor based on the delta E effect.