B18-Core EXAFS
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Hongman
Sun
,
Yu
Zhang
,
Chunfen
Wang
,
Mark A.
Isaacs
,
Ahmed I.
Osman
,
Yehong
Wang
,
David
Rooney
,
Youhe
Wang
,
Zifeng
Yan
,
Christopher M. A.
Parlett
,
Feng
Wang
,
Chunfei
Wu
Diamond Proposal Number(s):
[19850]
Abstract: Integrated carbon capture and utilization (ICCU) presents an ideal solution to address anthropogenic carbon dioxide (CO2) emissions from industry and energy sectors, facilitating CO2 capture and subsequent utilization through conversion into high-value chemicals, as opposed to current release into the atmosphere. Herein, we report the synergistic coupling of porous CaO, as a sorbent for CO2 capture, and Ni doped CeO2 nanorods, as catalytic sites for CO2 reduction. It is found that ceria is shown to possess the capacity for CO2 utilization, however, critically it only results in the generation of CO due to the weak CO-ceria bonding. The addition of Ni active sites gives rise to CH4 being the predominant product, via the strong interaction between Ni species and CO, which facilitates further reduction. Through tuning Ni loadings, we have evaluated the role of catalytic active site size, with a Ni loading of only 0.5 wt% providing optimal performance through the formation of sub-nanometer sized clusters. This near-atomic active site dispersion gives rise to CH4 productivity and selectivity of 1540 mmol g−1 Ni and 85.8%, respectively, with this optimal combination of catalyst and sorbent demonstrating high stability over 10 cycles of ICCU process. These observations in parallel with the synergistic coupling of earth-abundant, low-cost materials (CaO and Ni) will have broad implications on the design and implementation of high efficiency, cost-effective ICCU materials and processes.
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Jun 2022
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[25467]
Abstract: Tracking texture evolution during in situ loading is critical to understand and simulate the dynamic behaviour of microstructure in polycrystalline materials, yet conventional texture quantification methods are sometimes restricted due to various factors, such as acquisition time, sample environment and complex setup. To address this, a novel approach to extract texture information from single shot Time-Of-Flight neutron diffraction pattern has been developed. Another texture analysis approach based on single shot synchrotron X-ray diffraction has also been demonstrated. The effectiveness of two methods is assessed for polycrystalline Nickel-based superalloy polycrystalline samples possessing different textures. Both methods feature a moderate acquisition time of ~10 min and 30 s respectively, as well as a simplified setup which allows adding complex sample environments and the use of additional equipment. Comparison with the referential EBSD texture suggests that both approaches achieve a satisfactory match, though some details of the complex contour profiles in inverse pole figures may be missing. Besides that, a novel metric has been proposed to quantify the matching quality of pole figures. By employing the EPSC modelling approach, it is shown that the texture deviation due to the technique chosen for its evaluation exerts a subtle influence on th macro- and mesoscale simulation results, highlighting the significance of this approach for underpinning robust computational modelling.
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Apr 2022
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Open Access
Abstract: Crystals of metal hexachlorides Cs2MCl6 (M = Hf or Zr) have recently emerged as promising materials for scintillation applications due to their excellent energy resolution. In this work, we investigated the crystal structure and scintillation properties of Cs2HfCl6 and Cs2ZrCl6 crystals in the broad temperature range from 9 to 300 K. X-ray diffraction data confirmed the same cubic structure (space group Fm3m) for Cs2HfCl6 and Cs2ZrCl6 over the entire examined temperature range. The room temperature scintillation light yield of Cs2HfCl6 excited with a 137Cs γ-source is measured to be 24[thin space (1/6-em)]800 photons per MeV, while Cs2ZrCl6 exhibits 33[thin space (1/6-em)]900 photons per MeV resulting in energy resolutions of 5.3% and 4.5%, respectively. The alpha-to-beta ratio determined at room temperature for 5.5 MeV α-particles from an 241Am source is equal to 0.39 for Cs2HfCl6 and 0.35 for Cs2ZrCl6. The measurements of scintillation decay curves revealed complex kinetics due to delayed recombination processes. A tangible enhancement of the scintillation yield with heating is observed in the 125–150 K range. This effect is a manifestation of negative thermal quenching explained by thermal activation of trapped carriers. A model of the emission centre is proposed that consistently explains the observed changes of emission intensity with temperature in the crystals under study.
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Apr 2022
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I03-Macromolecular Crystallography
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Thomas W.
Thorpe
,
James R.
Marshall
,
Vanessa
Harawa
,
Rebecca E.
Ruscoe
,
Anibal
Cuetos
,
James D.
Finnigan
,
Antonio
Angelastro
,
Rachel S.
Heath
,
Fabio
Parmeggiani
,
Simon J.
Charnock
,
Roger M.
Howard
,
Rajesh
Kumar
,
David S. B.
Daniels
,
Gideon
Grogan
,
Nicholas J.
Turner
Diamond Proposal Number(s):
[9948]
Abstract: Chiral amine diastereomers are ubiquitous in pharmaceuticals and agrochemicals1, yet their preparation often relies on low-efficiency multi-step synthesis2. These valuable compounds must be manufactured asymmetrically, as their biochemical properties can differ based on the chirality of the molecule. Herein we characterize a multifunctional biocatalyst for amine synthesis, which operates using a mechanism that is, to our knowledge, previously unreported. This enzyme (EneIRED), identified within a metagenomic imine reductase (IRED) collection3 and originating from an unclassified Pseudomonas species, possesses an unusual active site architecture that facilitates amine-activated conjugate alkene reduction followed by reductive amination. This enzyme can couple a broad selection of α,β-unsaturated carbonyls with amines for the efficient preparation of chiral amine diastereomers bearing up to three stereocentres. Mechanistic and structural studies have been carried out to delineate the order of individual steps catalysed by EneIRED, which have led to a proposal for the overall catalytic cycle. This work shows that the IRED family can serve as a platform for facilitating the discovery of further enzymatic activities for application in synthetic biology and organic synthesis.
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Apr 2022
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I13-2-Diamond Manchester Imaging
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Saranarayanan
Ramachandran
,
Yi
Zhong
,
Stuart
Robertson
,
Christoforos
Panteli
,
Shuibao
Liang
,
Fan
Wu
,
Renqian
Zhou
,
Shashidhara
Marathe
,
Zhaoxia
Zhou
,
Andrew S.
Holmes
,
Sarah J.
Haigh
,
Changqing
Liu
,
Wajira
Mirihanage
Diamond Proposal Number(s):
[24151]
Abstract: Self-Propagating Exothermic Reactive (SPER) bonding with lead-free solders is potentially attractive for microelectronics assembly due to its highly localised heating and minimal thermal loading of the components and substrates. The transient dynamics of melting, wetting, solidification and defect formation during SPER bonding were observed using in-situ synchrotron X-ray imaging with sub-millisecond temporal resolution and the results were further analysed using electron microscopy and thermal modelling. In-situ imaging revealed the preferential melting of the solder and subsequent wetting of the substrate. Numerous air bubbles were observed to form at the bonding interface. The distribution of these bubbles was found to vary with the thermal conductivity and wettability of the substrates. These bubbles appear to reduce the effectiveness of bonding by promoting the formation of cracks and voids within the solder joint. Our results show that metallisation layers on the bonding substrate can influence the dynamics of melting for the solder materials and thereby directly influence the reliability of SPER interconnects.
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Apr 2022
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[21103]
Abstract: The effect of Strain Path Changes (SPCs) on the mechanical properties and crystal-level features of deformation for a single phase, ferritic steel has been investigated. SPCs were applied via a two-step deformation process, which included pre-straining via cold rolling, followed by uniaxial tension. The pre-strain magnitude and direction, as well as the tensile direction, varied between the specimens. The role of texture and micromechanics were examined in-situ, via Synchrotron X-ray Diffraction (SXRD), and ex-situ, via Electron Backscatter Diffraction (EBSD). Abrupt strain paths (i.e. strain paths where the pre-strain and the subsequent loading directions differ; here they are orthogonal) result in a significant ductility reduction, becoming more prevalent for high pre-strain magnitudes. The macroscopic response, as well as the texture configuration were greatly dependent on the pre-strain direction but were insensitive to the direction of uniaxial tension. Increasing pre-strain magnitudes resulted in a stagnation of lattice strain hardening rates in all macroscopic directions and in a significant increase in the Geometrically Necessary Dislocation (GND) densities. This was vastly increased for specimens rolled perpendicular to the as-received prior rolling direction. No correlation was found between the GND density and the grain orientation, eliminating this as a controlling ductility factor for BCC ferrite. Instead, the initial texture and the texture developed in a subsequent pre-strain influences the density of dislocations accumulated in all grains, and ultimately determines ductility.
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Apr 2022
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[11237]
Abstract: Stainless steel hardfacing alloys are being developed for wear and corrosion resistant applications in pressurised water reactor environments. Two examples of this, the austenitic Tristelle 5183 and triplex RR2450 were produced by gas-atomisation before undergoing consolidation using hot isostatic pressing. The phase evolution of these alloys during simulated hot isostatic pressing cycles was observed in-situ, using synchrotron x-ray diffraction. During these cycles, the metastability of the gas-atomised powders is revealed, which influences the rate of high-temperature transformation within the RR2450 alloy. Additionally, a high-strength silicide phase, named π-ferrosilicide, forms within these alloys. It decomposes by a eutectoid transformation, demonstrating a high carbon solubility within this phase. The observations of this study demonstrate the need to carefully consider the process parameters during hot isostatic pressing for such complex alloys, since alloy phase transformation rates are heavily influenced by the starting condition of the gas-atomised powder.
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Apr 2022
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[17222]
Abstract: Component failure due to cold dwell fatigue of titanium and its alloys is a long-standing problem which has significant safety and economic implications to the aviation industry. This can be addressed by understanding the governing mechanisms of time dependent plasticity behaviour of Ti at low temperatures. Here, stress relaxation tests were performed at four different temperatures on three major alloy systems: commercially pure titanium (two alloys with different oxygen content), Ti-6Al-4V (two microstructures with differing phase fractions) and Ti-6Al-2Sn-4Zr-Mo (two alloys with different Mo content =2 or 6, and portion of phase). Key parameters controlling the time dependent plasticity were determined as a function of temperature. Both activation volume and energy were found to increase with temperature in all six alloys. It was found that the dwell fatigue effect is more significant by oxygen alloying but is suppressed by the addition of Mo. The presence of the phase did not strongly affect the dwell fatigue, however, it was suppressed at high temperature due to the low strain rate and strain rate sensitivity.
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Apr 2022
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I14-Hard X-ray Nanoprobe
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Open Access
Abstract: A new stage design concept, the Delta Robot, is presented, which is a parallel kinematic design for scanning x-ray microscopy applications. The stage employs three orthogonal voice coils, which actuate parallelogram flexures. The design has a 3 mm travel range and achieves rms position jitter, integrated from 1 Hz to 1 kHz, of 2.8 and 1.3 nm perpendicular to the beam and 5.6 nm along the beam direction with loads up to 350 g. The Delta Robot design process used a mechatronics approach of iterative modeling and simulation to develop the system and validate performance. The design considerations, design process, stability, and operational performance on the hard x-ray nanoprobe at Diamond Light Source are presented.
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Apr 2022
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[17412, 8858]
Abstract: The effect of H+ ion irradiation on the structure and properties of a Cu50Zr50 metallic glass (MG) was investigated. High energy synchrotron X-ray diffraction results indicate that the glass maintains its amorphous nature after ion irradiation. As the ion fluence increases, the atomic bond length of MGs becomes shorter, whereas the nanohardness and Young’s modulus increase from 7.08±0.01 GPa and 111.3±1.1 GPa for the as-spun sample to 8.59±0.06 GPa and 123.1±1.3 GPa for the sample irradiated with 2×1016 cm-2 fluence. The corrosion potential of the studied MG in 1 mol/L HCl increases from -0.5953 V to -0.4519 V, suggesting an enhanced corrosion resistance of MGs after ion irradiation. The modification of mechanical properties and corrosion resistance can be interpreted from the ion irradiation-induced structural evolution. The results obtained here can be beneficial for better understanding the mechanical properties and corrosive behaviors of MGs under extreme conditions like ion irradiation and thus promoting their industrial applications.
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Apr 2022
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