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11 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2 [Next/Last]

Instruments / Technical Area	Publication Details	Published
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF) I22-Small angle scattering & Diffraction	Mixed hierarchical local structure in a disordered metal–organic framework Adam F. Sapnik , Irene Bechis , Sean M. Collins , Duncan N. Johnstone , Giorgio Divitini , Andrew J. Smith , Philip A. Chater , Matthew A. Addicoat , Timothy Johnson , David A. Keen , Kim E. Jelfs , Thomas D. Bennett Nature Communications 12 DOI: 10.1038/s41467-021-22218-9 Diamond Proposal Number(s): [20038, 24563] Open Access Show Abstract ▼ Abstract: Amorphous metal–organic frameworks (MOFs) are an emerging class of materials. However, their structural characterisation represents a significant challenge. Fe-BTC, and the commercial equivalent Basolite® F300, are MOFs with incredibly diverse catalytic ability, yet their disordered structures remain poorly understood. Here, we use advanced electron microscopy to identify a nanocomposite structure of Fe-BTC where nanocrystalline domains are embedded within an amorphous matrix, whilst synchrotron total scattering measurements reveal the extent of local atomic order within Fe-BTC. We use a polymerisation-based algorithm to generate an atomistic structure for Fe-BTC, the first example of this methodology applied to the amorphous MOF field outside the well-studied zeolitic imidazolate framework family. This demonstrates the applicability of this computational approach towards the modelling of other amorphous MOF systems with potential generality towards all MOF chemistries and connectivities. We find that the structures of Fe-BTC and Basolite® F300 can be represented by models containing a mixture of short- and medium-range order with a greater proportion of medium-range order in Basolite® F300 than in Fe-BTC. We conclude by discussing how our approach may allow for high-throughput computational discovery of functional, amorphous MOFs.	Apr 2021
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF)	Stepwise collapse of a giant pore metal–organic framework Adam F. Sapnik , Duncan N. Johnstone , Sean M. Collins , Giorgio Divitini , Alice M. Bumstead , Christopher W. Ashling , Philip A. Chater , Dean S. Keeble , Timothy Johnson , David A. Keen , Thomas D. Bennett Dalton Transactions 38 DOI: 10.1039/D1DT00881A Diamond Proposal Number(s): [20038, 20198] Open Access Show Abstract ▼ Abstract: Defect engineering is a powerful tool that can be used to tailor the properties of metal–organic frameworks (MOFs). Here, we incorporate defects through ball milling to systematically vary the porosity of the giant pore MOF, MIL-100 (Fe). We show that milling leads to the breaking of metal–linker bonds, generating additional coordinatively unsaturated metal sites, and ultimately causes amorphisation. Pair distribution function analysis shows the hierarchical local structure is partially retained, even in the amorphised material. We find that solvents can be used to stabilise the MIL-100 (Fe) framework against collapse, which leads to a substantial retention of porosity over the non-stabilised material.	Mar 2021
E02-JEM ARM 300CF	Local crystallinity in twisted cellulose nanofibers Tom Willhammar , Kazuho Daicho , Duncan N. Johnstone , Kayoko Kobayashi , Yingxin Liu , Paul A. Midgley , Lennart Bergström , Tsuguyuki Saito Acs Nano DOI: 10.1021/acsnano.0c08295 Diamond Proposal Number(s): [19130, 20614] Show Abstract ▼ Abstract: Cellulose is crystallized by plants and other organisms into fibrous nanocrystals. The mechanical properties of these nanofibers and the formation of helical superstructures with energy dissipating and adaptive optical properties depend on the ordering of polysaccharide chains within these nanocrystals, which is typically measured in bulk average. Direct measurement of the local polysaccharide chain arrangement has been elusive. In this study, we use the emerging technique of scanning electron diffraction to probe the packing of polysaccharide chains across cellulose nanofibers and to reveal local ordering of the chains in twisting sections of the nanofibers. We then use atomic force microscopy to shed light on the size dependence of the inherent driving force for cellulose nanofiber twisting. The direct measurement of crystalline twisted regions in cellulose nanofibers has important implications for understanding single-cellulose-fibril properties that influence the interactions between cellulose nanocrystals in dense assemblies. This understanding may enable cellulose extraction and separation processes to be tailored and optimized.	Jan 2021
E02-JEM ARM 300CF	Microstructural and mechanical characterisation of a second generation hybrid metal extrusion & bonding aluminium-steel butt joint Tina Bergh , Lise Sandnes , Duncan Neil Johnstone , Øystein Grong , Filippo Berto , Randi Holmestad , Paul Anthony Midgley , Per Erik Vullum Materials Characterization DOI: 10.1016/j.matchar.2020.110761 Diamond Proposal Number(s): [20527] Open Access Show Abstract ▼ Abstract: Hybrid metal extrusion & bonding (HYB) is a joining method that enables solid-state bonding by combining addition of aluminium filler material through continuous extrusion with pressure exerted by a rotating steel tool. This work presents mechanical and microstructural characterisation of a second generation HYB butt joint of aluminium alloy 6082 and structural steel S355. The ultimate tensile strength was measured to be in the range of 184–220 MPa, which corresponds to 60–72% joint efficiency. Digital image correlation analysis of the strain development during tensile testing revealed that root cracks formed, before the final fracture ran close to the aluminium-steel interface. A significant amount of residual aluminium was found on the steel fracture surface, especially in regions that experienced higher pressure during joining. Scanning and transmission electron microscopy revealed that the bond strength could be attributed to a combination of microscale mechanical interlocking and a discontinuous nanoscale interfacial Al-Fe-Si intermetallic phase layer. Analysis of scanning electron diffraction data acquired in a tilt series, indicated that the polycrystalline intermetallic phase layer contained the cubic αc phase. The results give insight into the bonding mechanisms of aluminium-steel joints and into the performance of HYB joints, which may be used to better understand and further develop aluminium-steel joining processes.	Nov 2020
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF)	A new route to porous metal–organic framework crystal–glass composites Shichun Li , Shuwen Yu , Sean M. Collins , Duncan N. Johnstone , Christopher W. Ashling , Adam F. Sapnik , Philip A. Chater , Dean S. Keeble , Lauren N. Mchugh , Paul A. Midgley , David A. Keen , Thomas D. Bennett Chemical Science 11, 9910 - 9918 DOI: 10.1039/D0SC04008H Diamond Proposal Number(s): [20038, 22632, 21979] Open Access Show Abstract ▼ Abstract: Metal–organic framework crystal–glass composite (MOF CGC) materials consist of a crystalline MOF embedded within a MOF–glass matrix. In this work, a new synthetic route to these materials is demonstrated through the preparation of two ZIF-62 glass-based CGCs, one with crystalline ZIF-67 and the other with crystalline UiO-66. Previous attempts to form these CGCs failed due to the high processing temperatures involved in heating above the melting point of ZIF-62. Annealing of the ZIF-62 glass above the glass transition with each MOF however leads to stable CGC formation at lower temperatures. The reduction in processing temperatures will enable the formation of a greatly expanded range of MOF CGCs.	Sep 2020
E02-JEM ARM 300CF	Direct imaging of correlated defect nanodomains in a metal-organic framework Duncan N. Johnstone , Francesca C. N. Firth , Clare P. Grey , Paul A. Midgley , Matthew J. Cliffe , Sean M. Collins Journal Of The American Chemical Society DOI: 10.1021/jacs.0c04468 Diamond Proposal Number(s): [20195, 21979, 20198] Show Abstract ▼ Abstract: Defect engineering can enhance key properties of metal-organic frameworks (MOFs). Tailoring the distribution of de-fects, for example in correlated nanodomains, requires characterization across length scales. However, a critical na-noscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the sub-nanometer imaging used to observe individual defects. Here, we demonstrate that the emerging technique of scanning electron diffraction (SED) can bridge this gap uniquely enabling both nanoscale crystallographic analysis and the low-dose formation of multiple diffraction contrast images for defect analysis in MOFs. We directly image defect nanodomains in the MOF UiO-66(Hf) over an area of ca. 1 000 nm and with a spatial resolution ca. 5 nm to reveal domain morphology and distribution. Based on these observations, we suggest possible crystal growth processes underpinning synthetic control of defect nanodomains. We also identify likely dislocations and small angle grain boundaries, illustrating that SED could be a key technique in developing the potential for engineering the distribution of defects, or “microstruc-ture”, in functional MOF design.	Jul 2020
E02-JEM ARM 300CF I14-Hard X-ray Nanoprobe	Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites Tiarnan A. S. Doherty , Andrew J. Winchester , Stuart Macpherson , Duncan N. Johnstone , Vivek Pareek , Elizabeth M. Tennyson , Sofiia Kosar , Felix U. Kosasih , Miguel Anaya , Mojtaba Abdi-Jalebi , Zahra Andaji-Garmaroudi , E. Laine Wong , Julien Madéo , Yu-Hsien Chiang , Ji-Sang Park , Young-Kwang Jung , Christopher E. Petoukhoff , Giorgio Divitini , Michael K. l. Man , Caterina Ducati , Aron Walsh , Paul A. Midgley , Keshav M. Dani , Samuel D. Stranks Nature 580, 360 - 366 DOI: 10.1038/s41586-020-2184-1 Diamond Proposal Number(s): [19023, 19793] Show Abstract ▼ Abstract: Halide perovskite materials have promising performance characteristics for low-cost optoelectronic applications. Photovoltaic devices fabricated from perovskite absorbers have reached power conversion efficiencies above 25 per cent in single-junction devices and 28 per cent in tandem devices. This strong performance (albeit below the practical limits of about 30 per cent and 35 per cent, respectively) is surprising in thin films processed from solution at low-temperature, a method that generally produces abundant crystalline defects. Although point defects often induce only shallow electronic states in the perovskite bandgap that do not affect performance, perovskite devices still have many states deep within the bandgap that trap charge carriers and cause them to recombine non-radiatively. These deep trap states thus induce local variations in photoluminescence and limit the device performance. The origin and distribution of these trap states are unknown, but they have been associated with light-induced halide segregation in mixed-halide perovskite compositions and with local strain, both of which make devices less stable. Here we use photoemission electron microscopy to image the trap distribution in state-of-the-art halide perovskite films. Instead of a relatively uniform distribution within regions of poor photoluminescence efficiency, we observe discrete, nanoscale trap clusters. By correlating microscopy measurements with scanning electron analytical techniques, we find that these trap clusters appear at the interfaces between crystallographically and compositionally distinct entities. Finally, by generating time-resolved photoemission sequences of the photo-excited carrier trapping process, we reveal a hole-trapping character with the kinetics limited by diffusion of holes to the local trap clusters. Our approach shows that managing structure and composition on the nanoscale will be essential for optimal performance of halide perovskite devices.	Apr 2020
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF)	Synthesis and properties of a compositional series of MIL-53(Al) metal-organic framework crystal-glass composites Christopher W. Ashling , Duncan N. Johnstone , Remo N. Widmer , Jingwei Hou , Sean M. Collins , Adam F. Sapnik , Alice M. Bumstead , Philip A. Chater , David A. Keen , Thomas Bennett Journal Of The American Chemical Society DOI: 10.1021/jacs.9b07557 Diamond Proposal Number(s): [20038, 20195] Open Access Show Abstract ▼ Abstract: Metal-organic framework crystal-glass composites (MOF-CGCs) are materials in which a crystalline MOF is dispersed within a MOF glass. In this work, we explore the room temperature stabilization of the open-pore form of MIL-53(Al), usually observed at high-temperature, which occurs upon encapsulation within a ZIF-62(Zn) MOF glass matrix. A series of MOF-CGCs containing different loadings of MIL-53(Al) were synthesized and characterized using X-ray diffraction and nuclear magnetic resonance spectroscopy. An upper limit of MIL-53(Al) that can be stabilized in the composite was determined for the first time. The nanostructure of the composites was probed using pair distribution function analysis and scanning transmission electron microscopy. Notably, the distribution and integrity of the crystalline compo-nent in a sample series was determined, and these findings related to the MOF-CGC gas adsorption capacity in order to identify the optimal loading necessary for maximum CO2 sorption capacity.	Sep 2019
E02-JEM ARM 300CF	Low-dose scanning electron diffraction microscopy of mechanochemically nanostructured pharmaceuticals Duncan N. Johnstone , Christopher Allen , Mohsen Danaie , Royston C. B. Copley , Jeffrey Brum , Angus I. Kirkland , Paul A. Midgley Microscopy And Microanalysis 25, 1746 - 1747 DOI: 10.1017/S1431927619009462 Diamond Proposal Number(s): [16983, 17991, 18488, 20527]	Aug 2019
E02-JEM ARM 300CF	Mapping non-crystalline nanostructure in beam sensitive systems with low-dose scanning electron pair distribution function analysis Joonatan E. M. Laulainen , Duncan N. Johnstone , Ivan Bogachev , Sean M. Collins , Louis Longley , Thomas Bennett , Paul A. Midgley Microscopy And Microanalysis 25, 1636 - 1637 DOI: 10.1017/S1431927619008912 Diamond Proposal Number(s): [16983, 19130, 20195, 21979]	Aug 2019

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