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32 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I15-1-X-ray Pair Distribution Function (XPDF) I15-Extreme Conditions	Correlating local structure and sodium storage in hard carbon anodes: Insights from pair distribution function analysis and solid-state NMR Joshua M. Stratford , Annette K. Kleppe , Dean S. Keeble , Philip A. Chater , Seyyed Shayan Meysami , Christopher J. Wright , Jerry Barker , Maria-Magdalena Titirici , Phoebe K. Allan , Clare P. Grey Journal Of The American Chemical Society DOI: 10.1021/jacs.1c06058 Diamond Proposal Number(s): [17785, 13681] Show Abstract ▼ Abstract: Hard carbons are the leading candidate anode materials for sodium-ion batteries. However, the sodium-insertion mechanisms remain under debate. Here, employing a novel analysis of operando and ex situ pair distribution function (PDF) analysis of total scattering data, supplemented by information on the local electronic structure provided by operando 23Na solid-state NMR, we identify the local atomic environments of sodium stored within hard carbon and provide a revised mechanism for sodium storage. The local structure of carbons is well-described by bilayers of curved graphene fragments, with fragment size increasing, and curvature decreasing with increasing pyrolysis temperature. A correlation is observed between the higher-voltage (slope) capacity and the defect concentration inferred from the size and curvature of the fragments. Meanwhile, a larger lower-voltage (plateau) capacity is observed in samples modeled by larger fragment sizes. Operando PDF data on two commercially relevant hard carbons reveal changes at higher-voltages consistent with sodium ions stored close to defective areas of the carbon, with electrons localized in the antibonding π*-orbitals of the carbon. Metallic sodium clusters approximately 13–15 Å in diameter are formed in both carbons at lower voltages, implying that, for these carbons, the lower-voltage capacity is determined by the number of regions suitable for sodium cluster formation, rather than by having microstructures that allow larger clusters to form. Our results reveal that local atomic structure has a definitive role in determining storage capacity, and therefore the effect of synthetic conditions on both the local atomic structure and the microstructure should be considered when engineering hard carbons.	Aug 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Glassy behaviour of mechanically amorphised ZIF-62 isomorphs Michael F. Thorne , Adam F. Sapnik , Lauren N. Mchugh , Alice M. Bumstead , Celia Castillo-Blas , Dean S. Keeble , Maria Diaz-Lopez , Philip A. Chater , David A. Keen , Thomas D. Bennett Chemical Communications DOI: 10.1039/D1CC03469C Diamond Proposal Number(s): [20038] Open Access Show Abstract ▼ Abstract: Zeolitic imidazolate frameworks (ZIFs) can be melt-quenched to form glasses. Here, we present an alternative route to glassy ZIFs via mechanically induced amorphisation. This approach allows various glassy ZIFs to be produced in under 30 minutes at room temperature, without the need for melt-quenching.	Aug 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Evolution of the local structure in the sol–gel synthesis of Fe3C nanostructures Matthew S. Chambers , Dean S. Keeble , Dean Fletcher , Joseph A. Hriljac , Zoe Schnepp Inorganic Chemistry 52 DOI: 10.1021/acs.inorgchem.0c03692 Diamond Proposal Number(s): [15959] Open Access Show Abstract ▼ Abstract: The sol–gel synthesis of iron carbide (Fe3C) nanoparticles proceeds through multiple intermediate crystalline phases, including iron oxide (FeOx) and iron nitride (Fe3N). The control of particle size is challenging, and most methods produce polydisperse Fe3C nanoparticles of 20–100 nm in diameter. Given the wide range of applications of Fe3C nanoparticles, it is essential that we understand the evolution of the system during the synthesis. Here, we report an in situ synchrotron total scattering study of the formation of Fe3C from gelatin and iron nitrate sol–gel precursors. A pair distribution function analysis reveals a dramatic increase in local ordering between 300 and 350 °C, indicating rapid nucleation and growth of iron oxide nanoparticles. The oxide intermediate remains stable until the emergence of Fe3N at 600 °C. Structural refinement of the high-temperature data revealed local distortion of the NFe6 octahedra, resulting in a change in the twist angle suggestive of a carbonitride intermediate. This work demonstrates the importance of intermediate phases in controlling the particle size of a sol–gel product. It is also, to the best of our knowledge, the first example of in situ total scattering analysis of a sol–gel system.	May 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Melting of hybrid organic–inorganic perovskites Bikash Kumar Shaw , Ashlea R. Hughes , Maxime Ducamp , Stephen Moss , Anup Debnath , Adam F. Sapnik , Michael F. Thorne , Lauren N. Mchugh , Andrea Pugliese , Dean S. Keeble , Philip Chater , Juan M. Bermudez-Garcia , Xavier Moya , Shyamal K. Saha , David A. Keen , François-Xavier Coudert , Frédéric Blanc , Thomas Bennett Nature Chemistry 119 DOI: 10.1038/s41557-021-00681-7 Diamond Proposal Number(s): [20038] Show Abstract ▼ Abstract: Several organic–inorganic hybrid materials from the metal–organic framework (MOF) family have been shown to form stable liquids at high temperatures. Quenching then results in the formation of melt-quenched MOF glasses that retain the three-dimensional coordination bonding of the crystalline phase. These hybrid glasses have intriguing properties and could find practical applications, yet the melt-quench phenomenon has so far remained limited to a few MOF structures. Here we turn to hybrid organic–inorganic perovskites—which occupy a prominent position within materials chemistry owing to their functional properties such as ion transport, photoconductivity, ferroelectricity and multiferroicity—and show that a series of dicyanamide-based hybrid organic–inorganic perovskites undergo melting. Our combined experimental–computational approach demonstrates that, on quenching, they form glasses that largely retain their solid-state inorganic–organic connectivity. The resulting materials show very low thermal conductivities (~0.2 W m−1 K−1), moderate electrical conductivities (10−3–10−5 S m−1) and polymer-like thermomechanical properties.	May 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
I15-1-X-ray Pair Distribution Function (XPDF)	Thermally-induced local structural transformations in Na0.5Bi0.5TiO3-KNbO3 ceramics Ge Wang , Anton Goetzee-Barral , Zhilun Lu , Dean S. Keeble , David A. Hall Journal Of The European Ceramic Society 35 DOI: 10.1016/j.jeurceramsoc.2021.01.040 Diamond Proposal Number(s): [17691] Show Abstract ▼ Abstract: The local symmetry of (1-x)Na0.5Bi0.5TiO3-xKNbO3 (NBT-xKN, x = 0.01-0.07) ceramics was thoroughly examined using high-energy synchrotron x-ray scattering and analysed using the Pair-Distribution Function (PDF) method. At room temperature, the structure of NBT-xKN (x = 0.01-0.07) ceramics was best refined using monoclinic C1c1 structures within the local-range (r<22 Å) and rhombohedral R3c within medium-range (22 Å 420 °C (above the temperature of the maximum dielectric peak, Tm), as confirmed by in-situ temperature-dependent PDF analysis.	Jan 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Metal-organic framework and inorganic glass composites Louis Longley , Courtney Calahoo , René Limbach , Yang Xia , Joshua M. Tuffnell , Adam F. Sapnik , Michael F. Thorne , Dean S. Keeble , David A. Keen , Lothar Wondraczek , Thomas D. Bennett Nature Communications 11 DOI: 10.1038/s41467-020-19598-9 Diamond Proposal Number(s): [20038] Open Access Show Abstract ▼ Abstract: Metal-organic framework (MOF) glasses have become a subject of interest as a distinct category of melt quenched glass, and have potential applications in areas such as ion transport and sensing. In this paper we show how MOF glasses can be combined with inorganic glasses in order to fabricate a new family of materials composed of both MOF and inorganic glass domains. We use an array of experimental techniques to propose the bonding between inorganic and MOF domains, and show that the composites produced are more mechanically pliant than the inorganic glass itself.	Nov 2020
I15-1-X-ray Pair Distribution Function (XPDF)	New insights into the application of pair distribution function studies to biogenic and synthetic hydroxyapatites Emily L. Arnold , Dean S. Keeble , Charlene Greenwood , Keith Rogers Scientific Reports 10 DOI: 10.1038/s41598-020-73200-2 Diamond Proposal Number(s): [18638, 23164] Open Access Show Abstract ▼ Abstract: Biogenic and synthetic hydroxyapatites are confounding materials whose properties remain uncertain, even after years of study. Pair distribution function (PDF) analysis was applied to hydroxyapatites in the 1970’s and 1980’s, but this area of research has not taken full advantage of the relatively recent advances in synchrotron facilities. Here, synchrotron X-ray PDF analysis is compared to techniques commonly used to characterise hydroxyapatite (such as wide angle X-ray scattering, Fourier-transform infrared spectroscopy and thermogravimetric analysis) for a range of biogenic and synthetic hydroxyapatites with a wide range of carbonate substitution. Contributions to the pair distribution function from collagen, carbonate and finite crystallite size were examined through principal component analysis and comparison of PDFs. Noticeable contributions from collagen were observed in biogenic PDFs when compared to synthetic PDFs (namely r < 15 Å), consistent with simulated PDFs of collagen structures. Additionally, changes in local structure were observed for PDFs of synthetic hydroxyapatites with differing carbonate content, notably in features near 4 Å, 8 Å and 19 Å. Regression models were generated to predict carbonate substitution from peak position within the PDFs.	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
I15-1-X-ray Pair Distribution Function (XPDF)	Fast operando X-ray pair distribution function using the DRIX electrochemical cell Maria Diaz-Lopez , Geoffrey L. Cutts , Phoebe K. Allan , Dean S. Keeble , Allan Ross , Valerie Pralong , Georg Spiekermann , Philip A. Chater Journal Of Synchrotron Radiation 27 DOI: 10.1107/S160057752000747X Diamond Proposal Number(s): [20893, 20094] Open Access Show Abstract ▼ Abstract: In situ electrochemical cycling combined with total scattering measurements can provide valuable structural information on crystalline, semi-crystalline and amorphous phases present during (dis)charging of batteries. In situ measurements are particularly challenging for total scattering experiments due to the requirement for low, constant and reproducible backgrounds. Poor cell design can introduce artefacts into the total scattering data or cause inhomogeneous electrochemical cycling, leading to poor data quality or misleading results. This work presents a new cell design optimized to provide good electrochemical performance while performing bulk multi-scale characterizations based on total scattering and pair distribution function methods, and with potential for techniques such as X-ray Raman spectroscopy. As an example, the structural changes of a nanostructured high-capacity cathode with a disordered rock-salt structure and composition Li4Mn2O5 are demonstrated. The results show that there is no contribution to the recorded signal from other cell components, and a very low and consistent contribution from the cell background.	Sep 2020

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