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11,795 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I13-2-Diamond Manchester Imaging	The importance of particle dispersion in electrical treeing and breakdown in nano-filled epoxy resin Siyuan Chen , Simon Rowland , James Carr , Malte Storm , Kwang-leong Choy , Adam J. Clancy International Journal Of Electrical Power & Energy Systems 129 DOI: 10.1016/j.ijepes.2021.106838 Diamond Proposal Number(s): [18215] Show Abstract ▼ Abstract: The addition of nano-fillers has been widely proposed as a method to enhance the dielectric properties of high voltage polymeric insulation, though there are mixed reports in the literature. Here the potential of silica nano-particles to extend the time to failure specifically through resistance to electrical tree growth in epoxy resin is determined. The benefit of silane treating the nano-particles before compounding is clearly established with regard to slowing tree growth and subsequent time to failure. The growth of trees in needle-plane samples is measured in the laboratory with loadings of 1, 3 and 5 wt% nano-filler. In all cases the average times to failure are extended, but silane treatment of the nano-particles prior to compounding yields much superior results. The emergence of a pronounced inception time before tree growth is also noted for the higher-filled, silane-treated cases. The average time to failure of silane-treated 5 wt% filled material was 28 times that of the unfilled resin. The improvement in performance between the nanocomposites with untreated and treated fillers is attributed to fewer agglomerations and improved dispersion of the filler in the treated cases. Measurements of Partial Discharge (PD) indicated significant differences in PD patterns during the growth of trees in the treated and untreated cases. This distinction may provide a quality control method for monitoring materials. In particular, long periods in which PDs were not measured were observed in the silane-treated cases. Visual imaging of tree growth in the unfilled material allowed the changing nature of the tree from fine to tree to dark tree to be observed as it grew. Corresponding PD measurements suggest the dark tree is gradually becoming conductive, and that growth of maximum PD measured is dependent on the relative rates of the growth of the tree and its carbonization. X-ray computer tomography identified significant differences in average tree channel diameters (a reduction from 2.8 µm to 2.0 µm for 1 wt% and 3 wt% cases). This implies that in addition to tree length changes, evaporated tree volumes also change and may explain the change in partial discharge characteristics observed.	Jul 2021
I07-Surface & interface diffraction	Heads or tails: Nanostructure and molecular orientations in organised erucamide surface layers Dajana Gubala , Laura Fox , Robert Harniman , Hadeel Hussain , Eric Robles , Meng Chen , Wuge H. Briscoe Journal Of Colloid And Interface Science 590, 506 - 517 DOI: 10.1016/j.jcis.2021.01.087 Diamond Proposal Number(s): [22176] Show Abstract ▼ Abstract: Hypothesis: Despite the widespread industrial usage of erucamide as a slip additive to modify polymer surface properties, a controversy appears to have persisted regarding the nanostructure of erucamide surface layers, particularly the molecular orientation at the outermost layer. The erucamide nanostructure and molecular orientation, along with its surface coverage, hydrophobicity, and adhesive response, can be tuned by simply varying the erucamide concentration in the solution from which the spin coated layer is prepared. Experiments: Synchrotron X-ray reflectivity (XRR) allowed a comprehensive characterisation of the out-of-plane structural parameters (e.g. molecular packing and thickness) of the erucamide layers prepared via spin coating from nonaqueous solution on silica. Complementary Atomic Force Microscopy (AFM) imaging with high lateral resolution revealed localised in-plane structures. Contact angle measurements provided information on the wettability of erucamide-coated surfaces. Peak Force Quantitative Nanomechanical Mapping (QNM) allowed a correlation between the erucamide nanostructure with the surface nanomechanical properties (i.e. adhesive response). Findings: Our results reveal erucamide surface nanostructures on silica as patchy monolayers, isolated circular bilayers/rounded rectangle-like aggregates and overlapping plate-like multilayers as the erucamide concentration in the spin coating solution was varied. In all the cases, XRR and AFM results were consistent with the picture that the erucamide tails were oriented outwards. The QNM adhesion force mapping of all the observed morphologies also supported this molecular orientation at the outermost erucamide monolayer. The wettability study further confirmed this conclusion with the observed increase in the surface hydrophobicity and coverage upon increasing erucamide concentration, with the macroscopic water contact angle θ = 92.9° ± 2.9° at the highest erucamide concentration of 2 wt%.	May 2021
I11-High Resolution Powder Diffraction	Early age hydration and application of blended magnesium potassium phosphate cements for reduced corrosion of reactive metals Laura J. Gardner , Claire L. Corkhill , Sam A. Walling , James E. Vigor , Claire A. Murray , Chiu C. Tang , John L. Provis , Neil C. Hyatt Cement And Concrete Research 143 DOI: 10.1016/j.cemconres.2021.106375 Diamond Proposal Number(s): [10038] Open Access Show Abstract ▼ Abstract: Magnesium potassium phosphate cements (MKPC) were investigated to determine their efficacy towards retardation of reactive uranium metal corrosion. Optimised low-water content, fly ash (FA) and blast furnace slag (BFS) blended MKPC formulations were developed and their fluidity, hydration behaviour, strength and phase assemblage investigated. In-situ time resolved synchrotron powder X-ray diffraction was used to detail the early age (~60 h) phase assemblage development and hydration kinetics, where the inclusion of BFS was observed to delay the formation of struvite-K by ~14 h compared to FA addition (~2 h). All samples set within this period, suggesting the possible formation of a poorly crystalline binding phase prior to struvite-K crystallisation. Long-term corrosion trials using metallic uranium indicated that MKPC systems are capable of limiting uranium corrosion rates (reduced by half), when compared to a UK nuclear industry grout, which highlights their potential application radioactive waste immobilisation.	May 2021
I13-2-Diamond Manchester Imaging	4D micro-scale, phase-contrast X-ray imaging and computed tomography of HMX-based polymer-bonded explosives during thermal runaway G. R. Parker , D. S. Eastwood , M. Storm , K. Vitharana , E. M. Heatwole , I. Lopez-pulliam , R. M. Broilo , P. M. Dickson , A. Martinez , Christoph Rau , N. K. Bourne Combustion And Flame 226, 478 - 489 DOI: 10.1016/j.combustflame.2020.12.025 Diamond Proposal Number(s): [15068, 16650, 18198] Show Abstract ▼ Abstract: High-resolution synchrotron x-ray radiography with computed tomography is used to observe the evolution of porosity created by thermal exposure in two HMX-based polymer-bonded explosive compositions; LX-04 and BX-63. The measurements were made in situ, over an extended period of time, during which the samples were heated on a slow-rate thermal trajectory. The tests ended with thermal-runaway to ignition after which the samples were consumed by combustion. The primary means of damage appears to be from mechanical debonding of the HMX-binder interface with secondary contribution from chemical decomposition. Confinement and binder properties affect the amount of porosity and permeability that develops. Additionally, observations were made describing the emergence and structure of an internal ignition volume, the formation and transport of a pre-ignition melt layer, and how the early stages of combustion were affected by material morphology, mechanical confinement and melt. The contact angle between molten HMX and the fluoropolymer, Viton A, is also presented. For the first time we have time-resolved x-ray images of ignition in sufficient detail to verify the mechanism of cookoff in polymer-bonded explosive compositions.	Apr 2021
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS B18-Core EXAFS	Study of the evolution of FeNxCy and Fe3C species in Fe/N/C catalysts during the oxygen reduction reaction in acid and alkaline electrolyte Álvaro García , Laura Pascual , Pilar Ferrer , Diego Gianolio , Georg Held , David C. Grinter , Miguel A. Peña , Maria Retuerto , Sergio Rojas Journal Of Power Sources 490 DOI: 10.1016/j.jpowsour.2021.229487 Diamond Proposal Number(s): [26554] Open Access Show Abstract ▼ Abstract: The nature and evolution of FeNxCy moieties in Fe/C/N catalysts has been studied by analysing Fe and N environments. TEM and Fe-XAS reveal the presence of FeNx moieties and Fe3C particles in the fresh catalyst. NEXAFS reveals the presence of two groups of (Fe)NxCy ensembles, namely (Fe)Nx-pyridinic and (Fe)Nx-pyrrolic. The architecture of the FeNxCy ensembles and their evolution during the ORR has been analysed by XAS, NEXAFS, and identical locations TEM. NxCy, FeNxCy and Fe3C species are partially removed during the ORR, resulting in the formation of Fe2O3 and Fe3O4 particles with different morphologies. The process is more severe in acid electrolyte than in alkaline one. (Fe)Nx-pyrrolic moieties are the main ones in the fresh catalysts, but (Fe)Nx-pyridinic groups are more stable after the ORR. The correlation between the evolution of the ORR activity and that of the FeNxCy ensembles indicates that FeNx-pyridinic ensembles are responsible for the ORR activity.	Apr 2021
I12-JEEP: Joint Engineering, Environmental and Processing	Growth dynamics of faceted Al13Fe4 intermetallic revealed by high-speed synchrotron X-ray quantification Zihan Song , Oxana V. Magdysyuk , Lei Tang , Tay Sparks , Biao Cai Journal Of Alloys And Compounds DOI: 10.1016/j.jallcom.2021.158604 Diamond Proposal Number(s): [19216] Show Abstract ▼ Abstract: High-speed synchrotron tomography was used to investigate the nucleation and growth dynamics of Al13Fe4 intermetallic during solidification of an Al-5wt%Fe alloy, providing new insights into its formation process. The majority of Al13Fe4 intermetallics nucleated near the surface oxide of the specimen and a few nucleated at Al13Fe4 phase. Al13Fe4 crystals grew into a variety of shapes, including plate-like, hexagonal tabular, stair-like and V-shaped, which can be attributed to the crystal structure of this compound and its susceptibility to twinning. Hole-like defects filled with aluminium melt were observed within the intermetallics. Oriented particle attachment mechanism was proposed to explain the formation of the Al13Fe4 intermetallic, which needs further experiments and simulation to confirm.	Apr 2021
I13-2-Diamond Manchester Imaging	Tracking lithium penetration in solid electrolytes in 3D by in-situ synchrotron X-ray computed tomography Shuai Hao , Sohrab R. Daemi , Thomas M. M. Heenan , Wenjia Du , Chun Tan , Malte Storm , Christoph Rau , Dan J. I. Brett , Paul R. Shearing Nano Energy 82 DOI: 10.1016/j.nanoen.2021.105744 Diamond Proposal Number(s): [22198] Show Abstract ▼ Abstract: Solid state batteries have attracted extensive attention, but the lithium penetration through the solid electrolyte remains a critical barrier to commercialisation and is not yet fully understood. In this study, the 3D morphological evolution of cracks with deposited lithium were tracked as they penetrated through the solid electrolyte during repetitive plating. This is achieved by utilising in-situ synchrotron X-ray computed tomography with high spatial and temporal resolutions. Thin-sheet cracks were observed to penetrate the solid electrolyte without immediate short-circuiting of the cell. Changes in their width and volume were quantified. By calculating the volume of deposited lithium, it was found that the lithium was only partially filled in cracks, and its filling ratio quickly dropped from 94.95% after the 1st plating to ca. 20% after the 4th plating. The filling process was revealed through tracking the line profile of grayscale along cracks. It was found that lithium grew much more slowly than cracks, so that the cracks near the cathode side were largely hollow and the cell could continue to operate. The deposited lithium after short circuit was segmented and its distribution was visualised. DVC analysis was applied to map local high stress and strain, which aggregated along cracks and significantly increased at areas where new cracks formed.	Apr 2021
	Atomic structure of the Mg66Zn30Ca4 metallic glass Karel Saksl , Ildikó Pethes , Pál Jóvári , Zuzana Molčanová , Juraj Durisin , Beáta Ballóková , László Temleitner , Stefan Michalik , Michaela Sulikova , Katarína Šuľová , Miloš Fejercak , Dagmara Varcholová , Rastislav Motýľ Journal Of Non-crystalline Solids 558 DOI: 10.1016/j.jnoncrysol.2021.120660 Show Abstract ▼ Abstract: Amorphous alloys consisting of elements present in the human body, such as magnesium, zinc and calcium, are currently extensively studied in order to utilize them as a material for biodegradable orthopaedic implants. amongst all Mg-Zn-Ca alloys investigated up to date, the Mg66Zn30Ca4 composition has the greatest potential for applications. Its critical casting thickness reaches a value of 5 mm, the compressive strength (716–854 MPa) is about 4 times the limit of human cortical bone while elastic modulus is (31 GPa) is only 3 times higher than that of human bone. During dissolution the alloy shows only marginal hydrogen evolution. Here we present a detailed, experiment-based structural investigation of Mg66Zn30Ca4. Structural and topological analysis of its atomic structure reveals a high number of predominantly icosahedral densely packed Zn-centred clusters. It is believed that the existence of these structural units is responsible for the suppression of internal diffusion and thus greatly improves glass formability.	Apr 2021
I04-Macromolecular Crystallography I24-Microfocus Macromolecular Crystallography	Functionalization of the BCL6 BTB domain into a noncovalent crystallization chaperone Thomas Zacharchenko , Stephanie Wright Iucrj 8 DOI: 10.1107/S2052252520015754 Diamond Proposal Number(s): [15378, 19248] Open Access Show Abstract ▼ Abstract: The production of diffraction-quality protein crystals is challenging and often requires bespoke, time-consuming and expensive strategies. A system has been developed in which the BCL6 BTB domain acts as a crystallization chaperone and promiscuous assembly block that may form the basis for affinity-capture crystallography. The protein of interest is expressed with a C-terminal tag that interacts with the BTB domain, and co-crystallization leads to its incorporation within a BTB-domain lattice. This strategy was used to solve the structure of the SH3 domain of human nebulin, a structure previously solved by NMR, at 1.56 Å resolution. This approach is simple and effective, requiring only routine protein complexation and crystallization screening, and should be applicable to a range of proteins.	Mar 2021
B18-Core EXAFS I20-Scanning-X-ray spectroscopy (XAS/XES)	Manganese containing copper aluminate catalysts: Genesis of structures and active sites for hydrogenation of aldehydes Christoph Dörfelt , Michelle Hammerton , David Martin , Alexander Wellmann , Clara C. Aletsee , Moniek Tromp , Klaus Köhler Journal Of Catalysis 395, 80 - 90 DOI: 10.1016/j.jcat.2020.12.017 Diamond Proposal Number(s): [16558] Show Abstract ▼ Abstract: Copper aluminate spinel (CuO.CuAl2O4) is the favoured Cr-free substitute for the copper chromite catalyst (CuO.CuCr2O4) in the industrial hydrogenation of aldehydes. New insights in the catalytic mechanism were obtained by systematically studying the structure and activity of these catalysts including effects of manganese as a catalyst component. The hydrogenation of butyraldehyde to butanol was studied as a model reaction and the active structure was characterised using X-ray diffraction, temperature programmed reduction, N2O chemisorption, EXAFS and XANES, including in-situ investigations. The active catalyst is a reduced spinel lattice that is stabilised by protons, with copper metal nanoparticles grown upon its surface. Incorporation of Mn into the spinel lattice has a profound effect on the spinel structure. Mn stabilises the spinel towards reduction of CuII to Cu0 by occupation of tetrahedral sites with Mn cations, but also causes decreased catalytic activity. Structural data, combined with the effect on catalysis, indicate a predominantly interface-based reaction mechanism, involving both the spinel and copper nanoparticle surface in protonation and reduction of the aldehyde. The electron reservoir of the metallic copper particles is regenerated by the dissociative adsorption and oxidation of H2 on the metal surface. The generated protons are stored in the spinel phase, acting as proton reservoir. Cu(I) species located within the spinel and identified by XANES are probably not involved in the catalytic cycle.	Mar 2021

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