Field Emission Scanning Electron Microscope with EBSD, EDS and CL

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For the research of the Geodynamics group as well as the other geoscientific and soil scientific working groups of the Faculty of Natural Sciences III of the Martin-Luther-University Halle-Wittenberg (MLU) the analysis of structure, crystallographic orientation and chemical composition of rocks and geomaterials is essential. The scientific problems require analysis capabilities in the range of centimeters to sub-micrometers. A scanning electron microscope (SEM) allows for the investigation of surface and phase contrast in this size range. Crystallographic orientations of the mineral phases are measured by an EBSD (Electron backscatter diffraction) detector. The chemical analysis is carried out by an EDS (Energy dispersive X-ray spectroscopy) detector. Zonations as well as the distribution of trace elements and crystal defects are imaged by a CL (Cathodoluminescence) detector. The planned investigations over at least five orders of magnitude (range of centimeters to sub-micrometers) necessitate both a high spatial resolution and also fast measurements in order to enable mappings of large sample areas. For that, a Schottky field emission scanning electron microscope (FEG-SEM) is indispensable as it provides the required beam parameters and beam stability.The FEG-SEM will primarily be used for the analysis of deformation fabrics in rocks. The spectrum of investigations ranges from nanoscale earthquake processes in the upper crust to the development of shear zones in rocks with up to millimeter-scale mineral grains as they occur in the lower crust and mantle of the Earth. For the research on the micro- or rather nano-mechanical processes of fracturing, frictional sliding or viscous creep high-resolution imaging techniques, crystallographic measurements and chemical results of the SEM analysis are necessary. Apart from these investigations that help to improve our understanding of plate tectonic processes and also earthquake nucleation, the new instrument shall be used to quantify the distribution and orientation of mineral grains to determine the physical and chemical properties of various rocks and geomaterials. This is important for geophysical and seismic studies or for technical applications of natural stone manufacture, tunnel construction, geothermal energy, ultimate waste disposal, ceramic and cementitious research as well as further topics concerning applied geology, mineral deposit exploration and technical mineralogy. Beside the wide field of geoscientific research goals the new instrument is also needed for soil scientific research at the MLU. Main topics are interactions between soil minerals and organic matter influenced by weathering, various environmental factors and climate change.