X-ray tomography (or computed tomography, or CT for short) is an imaging technique in which the sample is scanned step by step using X-rays. The images, taken at different angular positions, contain information about the absorption coefficient, which provides information about the internal material distribution. They are then processed into a 3D reconstruction using complex mathematical procedures.
Due to its resolution limit, the method is particularly suitable for the microstructural analysis of porous structures with particle sizes in the range of several micrometers (such as graphite anodes for lithium-ion batteries). Moreover, it allows the reconstruction of large volumes (compared to FIB/REM tomography) with edge lengths of several 100 μm. Another advantage is the non-destructive reconstruction, which means that the sample is not damaged or consumed during the procedure and can be analyzed again with other parameters or other methods if necessary. However, the advantage of the higher volume is offset by the lower maximum resolution and typically poorer contrast between the different phases compared to FIB/REM tomography.
Since late 2016, the IAM has an X-ray microscope (Xradia 520 Versa) with sub-μm resolution for 3D X-ray microscopy, which offers a spatial resolution below 0.7 µm with available voxel sizes of 70 nm [1]. Furthermore, reconstructions were performed for the IAM-ET in collaboration with RJL Micro&Analytic [2] using Skyscan 2011.
[1] www.zeiss.de/microscopy/de_de/produkte/roentgenmikroskopie/zeiss-xradia-520-versa.html#labdct