X-ray computer tomography (CT) is fast becoming an accepted tool within the materials science community for the acquisition of 3D images. Here the authors review the current state of the art as CT transforms from a qualitative diagnostic tool to a quantitative one. Our review considers first the image acquisition process, including the use of iterative reconstruction strategies suited to specific segmentation tasks and emerging methods that provide more insight (e.g. fast and high resolution imaging, crystallite (grain) imaging) than conventional attenuation based tomography. Methods and shortcomings of CT are examined for the quantification of 3D volumetric data to extract key topological parameters such as phase fractions, phase contiguity, and damage levels as well as density variations. As a non-destructive technique, CT is an ideal means of following structural development over time via time lapse sequences of 3D images (sometimes called 3D movies or 4D imaging). This includes information nee...

https://www.tandfonline.com/doi/pdf/10.1179/1743280413Y.0000000023

Quantitative X-ray tomography

http://research.engr.oregonstate.edu/immiscibles/sites/research.engr.oregonstate.edu.immiscibles/files/Papers/Wildenschild_Sheppard_AWR_2012.pdf

X-ray imaging and analysis techniques for quantifying pore-scale structure and processes in subsurface porous medium systems

Based on previously published hydroponic plant, planktonic bacterial, and soil microbial community research, manufactured nanomaterial (MNM) environmental buildup could profoundly alter soil-based food crop quality and yield. However, thus far, no single study has at once examined the full implications, as no studies have involved growing plants to full maturity in MNM-contaminated field soil. We have done so for soybean, a major global commodity crop, using farm soil amended with two high-production metal oxide MNMs (nano-CeO2 and -ZnO). The results provide a clear, but unfortunate, view of what could arise over the long term: (i) for nano-ZnO, component metal was taken up and distributed throughout edible plant tissues; (ii) for nano-CeO2, plant growth and yield diminished, but also (iii) nitrogen fixation—a major ecosystem service of leguminous crops—was shut down at high nano-CeO2 concentration. Juxtaposed against widespread land application of wastewater treatment biosolids to food crops, these findings forewarn of agriculturally associated human and environmental risks from the accelerating use of MNMs.

/pdf/soybean-susceptibility-to-manufactured-nanomaterials-with-2iaulaxvl7.pdf

Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption.

http://xrm.phys.northwestern.edu/research/pdf_papers/2007/withers_mater_today_2007.pdf

X-ray nanotomography

A high-resolution, nondestructive X-ray computed tomography (XCT) technique is applied to image the three-dimensional (3D) microstructure of a solid oxide fuel cell (SOFC) composed of a solid yttria-stabilized zirconia (YSZ) electrolyte and a porous nickel YSZ (Ni-YSZ) anode. The X-ray microscope uses the 8 keV Cu Kα line from a laboratory X-ray source, with a reflective condenser optic lens providing a spatial resolution of 42.7 nm. The reconstructed volume data is visualized as 3D images and further postprocessed in binary-image format to obtain structural parameters. The porosity is calculated using a voxel counting method, and tortuosity is evaluated by solving the Laplace equation. A 3D representation of the microstructure is used to calculate true structural parameters and carry out a detailed study of the gas transport within an SOFC electrode at the pore scale. Simulation of multicomponent mass transport and electrochemical reactions in the anode microstructure using the XCT data as geometric input illustrate the impact of this technique on SOFC modeling.

http://joshiscorner.com/files/publications/J005.pdf

Nondestructive Reconstruction and Analysis of SOFC Anodes Using X-ray Computed Tomography at Sub-50 nm Resolution

High-resolution X-ray computed tomography (XCT) enables nondestructive 3D imaging of complex structures, regardless of their state of crystallinity. This work describes a sub-50 nm resolution XCT system operating at 8 keV in absorption and Zemike phase contrast modes based on a commercially available Cu rotating anode laboratory X-ray source. The system utilizes a high efficiency reflective capillary condenser lens and high-resolution Fresnel zone plates with an outermost zone width of 35 nm and 700 nm structure height resulting in a spatial resolution better than 50 nm currently. Imaging a fragment of the solid oxide fuel cells (SOFC) with 50 nm resolution is presented as an application example of the XCT technique in materials science and nanotechnology.

/pdf/x-ray-computed-tomography-in-zernike-phase-contrast-mode-at-4tc5ayzqbh.pdf

X-ray computed tomography in Zernike phase contrast mode at 8 keV with 50-nm resolution using Cu rotating anode X-ray source

X-ray computed tomography (XCT) is a powerful nondestructive 3D imaging technique, which enables the visualization of the three dimensional structure of complex, optically opaque samples. High resolution XCT using Fresnel zone plate lenses has been confined in the past to synchrotron radiation centers due to the need for a bright and intense source of x-rays. This confinement severely limits the availability and accessibility of x-ray microscopes and the wide proliferation of this methodology. We are describing a sub-50nm resolution XCT system operating at 8 keV in absorption and Zernike phase contrast mode based on a commercially available laboratory x-ray source. The system utilizes high-efficiency Fresnel zone plates with an outermost zone width of 35 nm and 700 nm structure height resulting in a current spatial resolution better than 50 nm. In addition to the technical description of the system and specifications, we present application examples in the semiconductor field.

/pdf/high-resolution-x-ray-tomography-using-laboratory-sources-126jcn5tcx.pdf

High-resolution x-ray tomography using laboratory sources

X-ray computed tomography (CT) is a powerful nondestructive 3D imaging technique, which enables the visualization of the three dimensional internal structure of opaque materials such as semiconductor devices. Reports of high resolution CT research on life science, materials and semiconductor has mainly been confined to synchrotron radiation centers. This severely limits the availability and accessibility of x-ray microscopes and the wide proliferation of this methodology. We describe a sub-50nm resolution nanoCT system operating at 8 keV in Zernike phase contrast mode based on a commercially available laboratory x-ray source. The system utilizes high-efficiency Fresnel zone plates with an outermost zone width of 35nm resulting in spatial resolution better than 50 nm. The technical description of the system and failure analysis applications notably in visualizing voids, residues in metal interconnects, and competitive analysis in semiconductor devices will be discussed.

/pdf/non-destructive-failure-analysis-technique-with-a-laboratory-5401gcfxib.pdf

Non Destructive Failure Analysis Technique With a Laboratory Based 3D X-ray Nanotomography System

We describe a novel lab-based x-ray CT (computed tomography) system for rapid non invasive multi- length scale 3D characterization of internal structures of advanced and smart materials, from composites to sensors, from mm to sub 50 nm spatial resolution and with sample dimensions from several cm to microns. Notwithstanding most smart materials and sensors are in a matrix of low Z polymer or composites (making them challenging for x-ray radiography), the novel CT has excellent contrast. Several materials of interest to the military and home land security such as composites, polymers, micro and nano materials, protective materials against projectiles and blasting, smart self healing materials, fuel cell membranes and sensors and medical implants will be discussed. The key to this technology lies in proprietary x-ray optics, including Fresnel Zone plates and high resolution and high contrast detectors fabricated by Xradia.

/pdf/non-invasive-multi-length-scale-characterization-of-smart-elycy48c9p.pdf

Hongtao Cui

Papers

X-ray computed tomography in Zernike phase contrast mode at 8 keV with 50-nm resolution using Cu rotating anode X-ray source

High-resolution x-ray tomography using laboratory sources

Non Destructive Failure Analysis Technique With a Laboratory Based 3D X-ray Nanotomography System

Non Invasive, Multi-length Scale Characterization of Smart Materials, Membranes, Sensors with a novel high resolution and high contrast CT