Multi-scale Characterization of Crystalline Materials using X-ray Diffraction Imaging

QUICK INFORMATION
Type
Seminar
Start Date
15-01-2020 08:30
End Date
15-01-2020 09:30
Location
Room 500 - 501, Central Building
Speaker's name
Can YILDIRIM
Speaker's institute
CEA Grenoble
Contact name
Eva Jahn
Host name
Veijo Honkimaki
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Many industrial materials are composed of crystalline elements that have hierarchical structures of grains and domains that span over several length scales, from millimeters to nanometers. Understanding the link between these structures is of great importance in improving the macroscopic material performance. The need for probing the local crystal structure in various length scales favors diffraction-based approaches over spectroscopic methods. Recently, a novel synchrotron technique, dark-field X-ray microscopy (DFXM) was introduced, resolving strain and crystal orientation gradients within millimetre-sized bulk materials. By applying high-energy X-rays, this technique allows 3D mapping of local mosaicity and strain within embedded crystalline features with ~100 nm spatial resolution. In this work, DFXM was combined with nearfield Rocking Curve Imaging, 3DXRD and atomic simulations to investigate two different families of crystalline materials, polycrystalline and single crystalline. The first one is Fe-based polycrystalline materials (including Fe-3%Si, pearlitic steel, and ceramic reinforced steels) and explores phenomena of segregation, recovery, recrystallization and grain growth. The interaction of Sn solute with dislocations are also reported. The second one is single crystal materials (CdZnTe and HgCdTe) and focuses on the in-situ characterization of a fully operable infrared sensor along with the correlated defects of HgCdTe layers grown on CdZnTe substrates. The threading dislocations from substrate to layer, a spiral growth of the HgCdTe layer, temperature induced strain and its reversibility of the infrared sensor are discussed. Our results demonstrate how microscopic features affect macroscopic properties and eventually enable control for on-demand material properties.

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