A high-resolution, nondestructive X-ray computed tomography ͑XCT͒ technique is applied to image the three-dimensional ͑3D͒ microstructure of a solid oxide fuel cell ͑SOFC͒ composed of a solid yttria-stabilized zirconia ͑YSZ͒ electrolyte and a porous nickel YSZ ͑Ni-YSZ͒ anode. The X-ray microscope uses the 8 keV Cu K␣ 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.
The performance of MISTRAL is reported, the soft X-ray transmission microscopy beamline at the ALBA light source (Barcelona, Spain) which is primarily dedicated to cryo soft X-ray tomography (cryo-SXT) for three-dimensional visualization of whole unstained cells at spatial resolutions down to 30 nm (half pitch). Short acquisition times allowing for high-throughput and correlative microscopy studies have promoted cryo-SXT as an emerging cellular imaging tool for structural cell biologists bridging the gap between optical and electron microscopy. In addition, the beamline offers the possibility of imaging magnetic domains in thin magnetic films that are illustrated here with an example.
Epitaxial synthesis and properties of novel Co and Mn-doped Ge magnetic semiconductors were studied. Epitaxial growth of high quality films with high doping concentrations has been stabilized by the use of two dopants. The magnetic and transport properties of the system exhibit high T(C) and large magnetoresistance effects that can be controlled systematically by the doping concentration. The maximum T(C) achieved in the semiconducting materials is approximately 270 K at a composition of Co0.12Mn0.03Ge0.85.
Substantial improvements in the nanofabrication and characteristics of gold Fresnel zone plates yielded unprecedented resolution levels in hard-x-ray microscopy. Tests performed on a variety of specimens with 8–10keV photons demonstrated a first-order lateral resolution below 40nm based on the Rayleigh criterion. Combined with the use of a phase contrast technique, this makes it possible to view features in the 30nm range; good-quality images can be obtained at video rate, down to 50ms ∕frame. The important repercussions on materials science, nanotechnology, and the life sciences are discussed.
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