The functionality of many metastable or nanoscale materials (such as graphene or 2D layered materials) depends essentially on their structural perfection and compositional homogeneity on the atomic to mesoscopic scale. In-situ/ex-situ X-ray diffraction and various microscopy techniques are used to comprehensively explore these materials with respect to their structural, electronic and mechanical properties on all relevant length scales. The exact knowledge of these properties serves as a basis for the targeted adjustment and optimization of the material functionality.
Our research currently focuses on the following topical and methodological issues:
- Epitaxial relation and defects in 2D layered materials and heterostructures
- Composition fluctuations and off-stoichiometry in Fe5-xGeTe2 compounds
- Elastic and plastic properties of low dimensional systems
- Atomic structure of intercalated 2D metallic layers
- Synchrotron-based x-ray diffraction for in-situ (PHARAO at BESSY II, HZB) and ex-situ studies
- Nanofocused x-ray diffraction (ESRF Grenoble, PETRAIII Hamburg)
- Numerical analysis using Finite Element Method
- Scanning tunneling microscopy and spectroscopy
While conventional TEM delivers a 2D image of the 3D object, electron tomography provides a complete 3D reconstruction of the real objects. The method offers new possibilities for structural analysis and presentation down to the nanometer range. It is especially useful for material questions based on an inhomogeneous spatial distribution of structural units or on chemical composition fluctuations, as well as on complex defect structures (see Application Laboratory Electron Tomography).