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Project leader: Prof. Dr. rer. nat H. Schmidt
Funding period: 2010 - 2015
Funding body: DFG
Funding code: -
Nanocrystalline metals in the form of thin films are in a highly non-equilibrium state after their production using suitable deposition methods (e.g. magnetron sputtering). Annealing at temperatures close to room temperature leads to structural relaxation processes, which are accompanied by a temporal change in the concentration of free volumes in the grains and in the grain boundaries. In particular, there is a correlation with the relaxation of residual stresses. These processes can irreversibly change electrical, mechanical and magnetic properties.
The aim of this application is the experimental characterization and modelling of these processes in thin metal layers (5 -150 nm). A novel method based on the simultaneous in-situ measurement of lattice constants with X-ray diffraction (XRD) and the macroscopic length change with X-ray reflectometry (XRR) during isothermal annealing will be used for this purpose. By using synchrotron radiation, a time resolution in the range below one minute can be achieved. The method will be used to systematically investigate various cubic nanocrystalline metals (Cu, Pd and Fe) with different crystal structures and densities as a model system, as well as an application-relevant nanocrystalline metal-nitride compound ((-TiNx). An understanding of the structural relaxation kinetics as a function of temperature, layer thickness and grain size is to be derived from the results.