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X-ray microtomography combined with in-situ X-ray diffraction : structural studies from nano- to macroscale

Mardi 18 février 2014 15:30 - Duree : 1 heure
Lieu : Room 337, Central Building, ESRF, 6 Rue Jules Horowitz - Grenoble

Orateur : Jussi-Petteri SUURONEN (University of Helsinki, Finland)

X-rays are an extremely versatile probe for materials characterization : while conventional medical x-ray imaging is used to visualize structures with macroscopic dimensions, x-ray diffraction and spectroscopy provide information on phenomena at atomic length scales. Multimodal studies employing different x-ray methods are often necessary to understand the roles of differently scaled effects in the behavior of the system. While synchrotron sources will remain at the forefront of developing combined x-ray methods, adapting them for use with x-ray tube –based equipment is crucial to maximize their impact on research in any particular area. In this work, we have constructed a system that combines bench-top x-ray microtomography with localized x-ray diffraction or small-angle scattering. This unique home-lab setup allows performing both experiments sequentially without removing the sample from the setup. Using the microtomography reconstruction to target the scattering beam enables mapping selected crystallographic properties (e.g. lattice spacing or crystal orientation) with 200 micrometer resolution. Case studies of microstructural anisotropy in bentonite clay and the crystallographic analysis of submillimeter-sized micrometeorites are presented as application examples. Bentonite is a clay mixture which, due to its swelling and water retention properties, is considered for use as a buffer material in spent nuclear fuel repositories. In this case, combining small-angle x-ray scattering and microtomography with controlled humidity conditions allows correlating the local orientation of clay platelet stacks (i.e. tactoids) with the orientation of microcracks that develop when the clay is dried. In meteoritics, x-ray microtomography enables accurate determination of the volume and porosity of small meteorite fragments and micrometeorites ; these parameters are indicative of their atmospheric entry velocity. Using the combined microtomography/scattering system greatly facilitates subsequent diffraction experiments, which can then be used to determine their mineralogical composition and analyze the degree of crystallite orientation in relation to atmospheric entry velocity and microscale morphology.

Contact : isabelle.combe@esrf.fr

Discipline évènement : (Physique)
Entité organisatrice : (ESRF)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire ESRF)
Site de l'évènement : Polygone scientifique

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