Towards an x-ray-based coded aperture diffraction system for bulk material identification

Rare earth-doped ceria thin films are currently thoroughly studied to be used in miniaturized solid oxide cells, memristive devices and gas sensors. The employment in such different application fields derives from the most remarkable property of this material, namely ionic conductivity, occurring through the mobility of oxygen ions above a certain threshold temperature. This feature is in turn limited by the association of defects, which hinders the movement of ions through the lattice. In addition to these issues, ionic conductivity in thin films is dominated by the presence of the film/substrate interface, where a strain can arise as a consequence of lattice mismatch. A tensile strain, in particular, when not released through the occurrence of dislocations, enhances ionic conduction through the reduction of activation energy. Within this complex framework, high pressure X-ray diffraction investigations performed on the bulk material are of great help in estimating the bulk modulus of the material, and hence its compressibility, namely its tolerance toward the application of a compressive/tensile stress. In this review, an overview is given about the correlation between structure and transport properties in rare earth-doped ceria films, and the role of high pressure X-ray diffraction studies in the selection of the most proper compositions for the design of thin films.

Download Full-text

Three-dimensional structural measurement and material identification of an all-solid-state lithium-ion battery by X-Ray nanotomography and deep learning

Journal of Power Sources Advances ◽

10.1016/j.powera.2021.100048 ◽

2021 ◽

Vol 8 ◽

pp. 100048

Author(s):

M. Kodama ◽

A. Ohashi ◽

H. Adachi ◽

T. Miyuki ◽

A. Takeuchi ◽

...

Keyword(s):

Deep Learning ◽

Solid State ◽

Lithium Ion Battery ◽

Three Dimensional ◽

Lithium Ion ◽

Material Identification ◽

X Ray

Download Full-text

The influence of physical state on shikimic acid ozonolysis: a case for in situ microspectroscopy

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-10761-2014 ◽

2014 ◽

Vol 14 (19) ◽

pp. 10761-10772 ◽

Cited By ~ 28

Author(s):

S. S. Steimer ◽

M. Lampimäki ◽

E. Coz ◽

G. Grzinic ◽

M. Ammann

Keyword(s):

Degradation Rate ◽

Shikimic Acid ◽

Bulk Material ◽

Water Mixture ◽

Gas Uptake ◽

X Ray ◽

Scanning Transmission ◽

Dry Conditions ◽

Semi Solid

Abstract. Atmospheric soluble organic aerosol material can become solid or semi-solid. Due to increasing viscosity and decreasing diffusivity, this can impact important processes such as gas uptake and reactivity within aerosols containing such substances. This work explores the dependence of shikimic acid ozonolysis on humidity and thereby viscosity. Shikimic acid, a proxy for oxygenated reactive organic material, reacts with O3 in a Criegee-type reaction. We used an environmental microreactor embedded in a scanning transmission X-ray microscope (STXM) to probe this oxidation process. This technique facilitates in situ measurements with single micron-sized particles and allows to obtain near-edge X-ray absorption fine structure (NEXAFS) spectra with high spatial resolution. Thus, the chemical evolution of the interior of the particles can be followed under reaction conditions. The experiments show that the overall degradation rate of shikimic acid is depending on the relative humidity in a way that is controlled by the decreasing diffusivity of ozone with decreasing humidity. This decreasing diffusivity is most likely linked to the increasing viscosity of the shikimic acid–water mixture. The degradation rate was also depending on particle size, most congruent with a reacto-diffusion limited kinetic case where the reaction progresses only in a shallow layer within the bulk. No gradient in the shikimic acid concentration was observed within the bulk material at any humidity indicating that the diffusivity of shikimic acid is still high enough to allow its equilibration throughout the particles on the timescale of hours at higher humidity and that the thickness of the oxidized layer under dry conditions, where the particles are solid, is beyond the resolution of STXM.

Download Full-text

Investigation of Solvatomorphism and Its Photophysical Implications for Archetypal Trinuclear Au3(1-Methylimidazolate)3

Molecules ◽

10.3390/molecules26154404 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4404

Author(s):

Shengyang Guan ◽

David C. Mayer ◽

Christian Jandl ◽

Sebastian J. Weishäupl ◽

Angela Casini ◽

...

Keyword(s):

Crystal Structure ◽

Solid State ◽

Density Functional ◽

Bulk Material ◽

Variable Temperature ◽

Active Phase ◽

Solvent Free ◽

X Ray Diffraction ◽

X Ray ◽

Aurophilic Interactions

A new solvatomorph of [Au3(1-Methylimidazolate)3] (Au3(MeIm)3)—the simplest congener of imidazolate-based Au(I) cyclic trinuclear complexes (CTCs)—has been identified and structurally characterized. Single-crystal X-ray diffraction revealed a dichloromethane solvate exhibiting remarkably short intermolecular Au⋯Au distances (3.2190(7) Å). This goes along with a dimer formation in the solid state, which is not observed in a previously reported solvent-free crystal structure. Hirshfeld analysis, in combination with density functional theory (DFT) calculations, indicates that the dimerization is generally driven by attractive aurophilic interactions, which are commonly associated with the luminescence properties of CTCs. Since Au3(MeIm)3 has previously been reported to be emissive in the solid-state, we conducted a thorough photophysical study combined with phase analysis by means of powder X-ray diffraction (PXRD), to correctly attribute the photophysically active phase of the bulk material. Interestingly, all investigated powder samples accessed via different preparation methods can be assigned to the pristine solvent-free crystal structure, showing no aurophilic interactions. Finally, the observed strong thermochromism of the solid-state material was investigated by means of variable-temperature PXRD, ruling out a significant phase transition being responsible for the drastic change of the emission properties (hypsochromic shift from 710 nm to 510 nm) when lowering the temperature down to 77 K.

Download Full-text

Pencil beam coded aperture x-ray scatter imaging

Optics Express ◽

10.1364/oe.20.016310 ◽

2012 ◽

Vol 20 (15) ◽

pp. 16310 ◽

Cited By ~ 52

Author(s):

Kenneth MacCabe ◽

Kalyani Krishnamurthy ◽

Amarpreet Chawla ◽

Daniel Marks ◽

Ehsan Samei ◽

...

Keyword(s):

Coded Aperture ◽

Pencil Beam ◽

X Ray

Download Full-text

A coded aperture microscope for X-ray fluorescence full-field imaging

Journal of Synchrotron Radiation ◽

10.1107/s1600577520012308 ◽

2020 ◽

Vol 27 (6) ◽

pp. 1703-1706

Author(s):

D. P. Siddons ◽

A. J. Kuczewski ◽

A. K. Rumaiz ◽

R. Tappero ◽

M. Idir ◽

...

Keyword(s):

Silicon Nitride ◽

Near Field ◽

Coded Aperture ◽

Full Field ◽

X Ray ◽

Silicon Nitride Membrane ◽

Coded Apertures ◽

Redundant Arrays ◽

Field Imaging ◽

Good Contrast

The design and construction of an instrument for full-field imaging of the X-ray fluorescence emitted by a fully illuminated sample are presented. The aim is to produce an X-ray microscope with a few micrometers spatial resolution, which does not need to scan the sample. Since the fluorescence from a spatially inhomogeneous sample may contain many fluorescence lines, the optic which will provide the magnification of the emissions must be achromatic, i.e. its optical properties must be energy-independent. The only optics which fulfill this requirement in the X-ray regime are mirrors and pinholes. The throughput of a simple pinhole is very low, so the concept of coded apertures is an attractive extension which improves the throughput by having many pinholes, and retains the achromatic property. Modified uniformly redundant arrays (MURAs) with 10 µm openings and 50% open area have been fabricated using gold in a lithographic technique, fabricated on a 1 µm-thick silicon nitride membrane. The gold is 25 µm thick, offering good contrast up to 20 keV. The silicon nitride is transparent down into the soft X-ray region. MURAs with various orders, from 19 up to 73, as well as their respective negative (a mask where open and closed positions are inversed compared with the original mask), have been made. Having both signs of mask will reduce near-field artifacts and make it possible to correct for any lack of contrast.

Download Full-text