Vision transformer for multi-domain phase retrieval in coherent diffraction imaging
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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Engineering topics
Robinson, Ian
Publications and source records attributed to Robinson, Ian.
Scaffold Infiltrated Cathodes for Low-Temperature Solid Oxide Fuel Cells
Not provided.
Materials Science↗
Resolving length-scale-dependent transient disorder through an ultrafast phase transition
Abstract Material functionality can be strongly determined by structure extending only over nanoscale distances. The pair distribution function presents an opportunity for structural studies beyond idealized crystal models and to investigate structure over varying length scales. Applying this method with ultrafast time resolution has the potential to similarly disrupt the study of structural dynamics and phase transitions. Here we demonstrate such a measurement of CuIr 2 S 4 optically pumped from its low-temperature Ir-dimerized phase. Dimers are optically suppressed without spatial correlation, generating a structure whose level of disorder strongly depends on the length scale. The redevelopment of structural ordering over tens of picoseconds is directly tracked over both space and time as a transient state is approached. This measurement demonstrates the crucial role of local structure and disorder in non-equilibrium processes as well as the feasibility of accessing this information with state-of-the-art XFEL facilities.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Suppressing strain propagation in ultrahigh-Ni cathodes during fast charging via epitaxial entropy-assisted coating
Surface reconstruction and the associated severe strain propagation have long been reported as the major cause of cathode failure during fast charging and long-term cycling. Despite tremendous attempts, no known strategies can simultaneously address the electro-chemomechanical instability without sacrificing energy and power density. Here we report an epitaxial entropy-assisted coating strategy for ultrahigh-Ni LiNi x Co y Mn 1-x-y O 2 (x ≥ 0.9) cathodes via an oriented attachment-driven reaction between Wadsley-Roth phase-based oxides and the layered-oxide cathodes. Further, the high anti-cracking and anti-corrosion tolerances as well as the fast ionic transport of the entropy-assisted surface effectively improved the fast charging/discharging capability, wide temperature tolerance and thermal stability of the ultrahigh-Ni cathodes. Comprehensive analysis from the primary and secondary particle level to the electrode level using multi-scale in situ synchrotron X-ray probes reveals greatly reduced lattice dislocations, anisotropic lattice strain and oxygen release as well as improved bulk/local structural stability, even when charging beyond the threshold state of charge (75%) of layered cathodes. Layered Ni-rich oxide cathodes are susceptible to challenges with surface reconstruction and strain propagation, limiting their cyclability. The authors propose a solution involving oriented attachment-driven reactions, utilizing Wadsley-Roth nanocrystals and layered oxide to induce an epitaxial entropy-assisted coating, effectively addressing these issues.
25 ENERGY STORAGE↗
Direct utilization of gaseous fuels in metal supported solid oxide fuel cells
Direct utilization and internal reforming of gaseous fuels is investigated on symmetric-architecture metal supported solid oxide fuel cells (MS-SOFCs) with thin ceramic electrolyte and scaffold backbone layers, and low cost ferritic stainless steel supports on both sides. Infiltrated Pr-oxide and Ni/samarium-doped ceria catalysts are added to the cathode and anode electrodes, respectively. Initial performance and durability is evaluated for MS-SOFCs operating with natural gas, propane, ammonia, and dimethyl ether at 700 °C. Cells for natural gas and propane utilize a novel high entropy alloy (HEA) catalyst for internal reforming with performance and degradation rates similar to H 2 (0.5W cm -2 and ~12%/100 h). In conclusion, initial testing with sulfur shows reversible degradation for levels found in natural gas and irreversible degradation for higher levels found in commercial propane. Overall, MS-SOFCs show successful fuel flexibility.
08 HYDROGEN↗
Origin of structural degradation in Li-rich layered oxide cathode
Li- and Mn-rich (LMR) cathode materials that utilize both cation and anion redox can yield substantial increases in battery energy density 1,2,3 . However, although voltage decay issues cause continuous energy loss and impede commercialization, the prerequisite driving force for this phenomenon remains a mystery 3,4,5,6 In this work, with in situ nanoscale sensitive coherent X-ray diffraction imaging techniques, we reveal that nanostrain and lattice displacement accumulate continuously during operation of the cell. Evidence shows that this effect is the driving force for both structure degradation and oxygen loss, which trigger the well-known rapid voltage decay in LMR cathodes. By carrying out micro- to macro-length characterizations that span atomic structure, the primary particle, multiparticle and electrode levels, we demonstrate that the heterogeneous nature of LMR cathodes inevitably causes pernicious phase displacement/strain, which cannot be eliminated by conventional doping or coating methods. We therefore propose mesostructural design as a strategy to mitigate lattice displacement and inhomogeneous electrochemical/structural evolutions, thereby achieving stable voltage and capacity profiles. These findings highlight the significance of lattice strain/displacement in causing voltage decay and will inspire a wave of efforts to unlock the potential of the broad-scale commercialization of LMR cathode materials.
25 ENERGY STORAGE↗
Combining Multicolor FISH with Fluorescence Lifetime Imaging for Chromosomal Identification and Chromosomal Sub Structure Investigation
Understanding the structure of chromatin in chromosomes during normal and diseased state of cells is still one of the key challenges in structural biology. Using DAPI staining alone together with Fluorescence lifetime imaging (FLIM), the environment of chromatin in chromosomes can be explored. Fluorescence lifetime can be used to probe the environment of a fluorophore such as energy transfer, pH and viscosity. Multicolor FISH (M-FISH) is a technique that allows individual chromosome identification, classification as well as assessment of the entire genome. Here we describe a combined approach using DAPI as a DNA environment sensor together with FLIM and M-FISH to understand the nanometer structure of all 46 chromosomes in the nucleus covering the entire human genome at the single cell level. Upon DAPI binding to DNA minor groove followed by fluorescence lifetime measurement and imaging by multiphoton excitation, structural differences in the chromosomes can be studied and observed. This manuscript provides a blow by blow account of the protocol required to perform M-FISH-FLIM of whole chromosomes.
59 BASIC BIOLOGICAL SCIENCES↗
Complex imaging of phase domains by deep neural networks
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Wu, Longlong↗
Electronic nematicity in Sr 2 RuO 4
We have measured the angle-resolved transverse resistivity (ARTR), a sensitive indicator of electronic anisotropy, in high-quality thin films of the unconventional superconductor Sr 2 RuO 4 grown on various substrates. The ARTR signal, heralding the electronic nematicity or a large nematic susceptibility, is present and substantial already at room temperature and grows by an order of magnitude upon cooling down to 4 K. In Sr 2 RuO 4 films deposited on tetragonal substrates the highest-conductivity direction does not coincide with any crystallographic axis. In films deposited on orthorhombic substrates it tends to align with the shorter axis; however, the magnitude of the anisotropy stays the same despite the large lattice distortion. These are strong indications of actual or incipient electronic nematicity in Sr 2 RuO 4 .
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Unusual Breathing Behavior of Optically Excited Barium Titanate Nanocrystals
Coherent X-ray diffraction patterns were recorded by using an X-ray free-electron laser to illuminate barium titanate nanocrystals as a function of time delay after laser excitation. Rather than seeing any significant thermal expansion effects, the diffraction peaks were found to move perpendicular to the momentum transfer direction. This suggests a laser driven rotation of the crystal lattice, which is delayed by the aggregated state of the crystals. Internal deformations associated with crystal contacts were also observed.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Strain and Electronic Nematicity in La 2- x Sr x CuO 4
Electronic nematicity has previously been observed in La 2- x Sr x CuO 4 thin films by the angle resolved transverse resistivity method with a director whose orientation is always pinned to the crystal axes when the film is grown on an orthorhombic substrate but not when the substrate is tetragonal. Furthermore we report on measurements of thin films grown on (tetragonal) LaSrAlO 4 and subsequently placed in an apparatus that allows the application of uniaxial compressive strain.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Domain Texture of the Orthorhombic Phase of La 2-x Ba x CuO 4
Bragg Coherent Diffraction Imaging (BCDI) experiments have been carried out at the Advanced Photon Source using a new cryostat system developed to achieve high mechanical stability and low vibrations. Here, we measured the (012) LTO Bragg peak which is unique to the low-temperature orthorhombic (LTO) phase of micron-sized crystals of the High-temperature Superconductor La 2-x Ba x CuO 4 (LBCO) to study the formation of structural domains. Each time the sample was cooled into the orthorhombic phase, the diffraction pattern of domains was different. Finally, this confirms the interpretation of pinning of the lower-temperature Charge Density Wave domains observed in coherent resonant X-ray speckle correlation analysis experiments.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Three-dimensional characterization of hardened paste of hydrated tricalcium silicate by serial block-face scanning electron microscopy
With the application of a three-dimensional (3D) characterization technique, serial block-face scanning electron microscopy (SBFSEM), the 3D microstructure of a hydrated cement monomineral, tricalcium silicate (C 3 S), was measured with nanoscale resolution. The 3D morphologies of anhydrous particles, hydrated products, and capillary pores were visualized. Closed and open pores were discovered inside an anhydrous particle. The size and distribution of both the anhydrous C 3 S particles and their capillary pores were analyzed quantitatively and the porosity was determined to be 9%. The distribution of pores was found to be in a good agreement with the inner and outer product model of Hu et. al., with an inner shell distance of 860 nm. Here, considering the spatial resolution of the instrument and the volume of sample measured, most pores in this experiment could be characterized as capillary pores.
3D microstructure↗
Three-dimensional structure investigation of Waterborne Paint by Electron Microscopic Imaging
In this paper, the three-dimensional (3D) spatial structure of a TiO 2 coated waterborne paint film has been successfully investigated by serial block-face scanning electron microscopy (SBFSEM). The investigation clearly shows the spatial distribution of the TiO2 particles in the paint film and illustrates the degree of dispersion of the particles in the composite material. More than 58% of the volume of the TiO 2 particles are between 1.0 × 10 6 nm 3 to 1.0 × 10 7 nm 3 and the minimum distance between different particles can be detected is 124 nm. Different types of voids can be found in the 3D image of the cured water-borne paint film: voids that exist in the paint itself, voids produced by particle shedding, water evaporating and particles stacking. Among these voids, the ones produced by particle shedding is a cutting artefact. The research provides a different approach to clearly present the 3D spatial structure of paints and can clearly illustrate different kinds of voids inside the water-borne paint. While the resulting 3D structure of the paint, especially the different voids are important for further systematic research on the relationships between the spatial microstructure and the physical and chemical properties of the water-borne paint.
36 MATERIALS SCIENCE↗
Pore structure development during hydration of tricalcium silicate by X-ray nano-imaging in three dimensions
We report that tricalcium silicate (C 3 S) is the most important component among the four main clinker phases of Portland cement. Pure C 3 S is widely used as a simplified model system of cement in various researches. However, the spatial structure development of cement, even pure C 3 S during hydration at the nano-scale has been rarely directly reported. In this work, X-ray nano-computed tomography (X-ray Nano-CT), a non-destructive X-ray analytical method, was used to study the hydration of a pure C 3 S sample with a water/C 3 S mass ratio of 0.5. The three-dimensional (3D) structure of the hydrating C 3 S specimen was investigated to see the internal pore structure evolution within the hardened C 3 S paste. Investigation of the 3D structural development of the C 3 S specimen at different hydration times was performed to monitor the changes of pore shapes and sizes/volumes. Lastly, it is found that volumes of the sealed pores generally grow larger, and the open pores become smaller while the volume and the external morphology of the whole hardened C 3 S paste remains almost the same during hydration.
36 MATERIALS SCIENCE↗
Coherent diffraction study of calcite crystallization during the hydration of tricalcium silicate
The aim of this work is using Bragg coherent X-ray diffraction imaging (BCDI) to study the calcite crystallization during carbonation of hydrated tricalcium silicate (C 3 S). Portland cement is a very complex synthesized product whose 50–70% mass is composed of C 3 S, which is the most important phase to produce calcium silicate hydrates and calcium hydroxide. Hence, its hydration contributes greatly to the hydration of cement and later to the carbonation of cement products when it reacts with CO 2 , often from the air, to form calcium carbonates. BCDI has emerged in the last decade as a promising high-resolution lens-less imaging approach for characterization of various samples. It has made significant progress with the development of X-ray sources and phase-retrieval algorithms. BCDI allows for imaging the whole three-dimensional structure of micro- and sub-micro- crystalline materials and can show the strain distribution at the nanometer spatial resolution. Finally, results show that calcite crystallization follows a through-solution reaction and the growth model of the calcite crystal can be explained by using “phase domain” theory. In conclusion, during carbonation, calcite crystals grow by increasing the number of phase domains within them while the domain size remains at about 200–300 nm.
36 MATERIALS SCIENCE↗
Investigation of Three-Dimensional Microstructure of Tricalcium Silicate (C 3 S) by Electron Microscopy
A serial block-face scanning electron microscopy (SBFSEM) system, composed of a scanning electron microscope (SEM) and an ultra-microtome installed within the SEM vacuum chamber, has been used to characterize the three-dimensional (3D) microstructure of tricalcium silicate (C 3 S) grains embedded in epoxy resin. A selection of C 3 S grains were segmented and rendered with 3D-image processing software, which allowed the C 3 S grains to be clearly visualized and enabled statistically quantitative analysis. The results show that about 5% of the C 3 S grains have volumes larger than 1 μm 3 and the average volume of the grains is 25 μm 3 . Pores can also be clearly seen in the biggest C 3 S grain, the volume of which is 3.6 × 10 4 μm 3 , and the mean volume and total volume of all the pores within this grain are 4.8 μm 3 and 3.0 × 10 3 μm 3 , respectively. This work provides a new approach for the characterization of the 3D spatial structure of raw C 3 S materials, and the resulting 3D structure of the raw C 3 S is important for further systematic research on the relationships between the spatial microstructure and the hydration kinetics of C 3 S and other cement minerals.
36 MATERIALS SCIENCE↗