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

Instruments / Technical Area	Publication Details	Published
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
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
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
I15-1-X-ray Pair Distribution Function (XPDF)	Insights into the electrochemical reduction products and processes in silica anodes for next‐generation lithium‐ion batteries Jake E. Entwistle , Samuel G. Booth , Dean S. Keeble , Faisal Ayub , Maximilian Yan , Serena A. Corr , Denis J. Cumming , Siddharth V. Patwardhan Advanced Energy Materials 278 DOI: 10.1002/aenm.202001826 Diamond Proposal Number(s): [2257] Open Access Show Abstract ▼ Abstract: The use of silica as a lithium‐ion battery anode material requires a pretreatment step to induce electrochemical activity. The partially reversible electrochemical reduction reaction between silica and lithium has been postulated to produce silicon, which can subsequently reversibly react with lithium, providing stable capacities higher than graphite materials. Up to now, the electrochemical reduction pathway and the nature of the products were unknown, thereby hampering the design, optimization, and wider uptake of silica‐based anodes. Here, the electrochemical reduction pathway is uncovered and, for the first time, elemental silicon is identified as a reduction product. These insights, gleaned from analysis of the current response and capacity increase during reduction, conclusively demonstrated that silica must be reduced to introduce reversible capacity and the highest capacities of 600 mAh g−1 are achieved by using a constant load discharge at elevated temperature. Characterization via total scattering X‐ray pair distribution function analysis reveal the reduction products are amorphous in nature, highlighting the need for local structural methods to uncover vital information often inaccessible by traditional diffraction. These insights contribute toward understanding the electrochemical reduction of silica and can inform the development of pretreatment processes to enable their incorporation into next‐generation lithium‐ion batteries.	Sep 2020
I15-1-X-ray Pair Distribution Function (XPDF)	Structure of anisole derivatives by total neutron and X-ray scattering: Evidences of weak C H⋯O and C H⋯π interactions in the liquid state Alessandro Triolo , Fabrizio Lo Celso , Natalia V. Plechkova , Francesca Leonelli , Sabrina Gärtner , Dean S. Keeble , Olga Russina Journal Of Molecular Liquids DOI: 10.1016/j.molliq.2020.113795 Diamond Proposal Number(s): [23149] Show Abstract ▼ Abstract: High resolution, total neutron and X-ray scattering data have been used in synergy with Molecular Dynamics simulations to access atomistic scale insight into the structure of anisole and 2,3,5-trimethylanisole, two aromatic compounds bearing an electron-donating methoxy group. A detailed description is provided for the main interactions occurring in these systems, including π-π stacking and weak hydrogen bonding correlations: CH⋯O and CH⋯π. The existence of preferential orientations of the first shell coordinating molecules and the specific nature of the interactions involving the π cloud and the polar methoxy group have been reported and discussed.	Jul 2020

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