I15-1-X-ray Pair Distribution Function (XPDF)
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Vahid
Nozari
,
Ayda Nemati Vesali
Azar
,
Roman
Sajzew
,
Celia
Castillo-Blas
,
Ayano
Kono
,
Martin
Oschatz
,
David A.
Keen
,
Philip A.
Chater
,
Georgina P.
Robertson
,
James M. A.
Steele
,
Luis
León-Alcaide
,
Alexander
Knebel
,
Christopher W.
Ashling
,
Thomas D.
Bennett
,
Lothar
Wondraczek
Diamond Proposal Number(s):
[29957]
Open Access
Abstract: Metal-organic framework (MOF) composite materials containing ionic liquids (ILs) have been proposed for a range of potential applications, including gas separation, ion conduction, and hybrid glass formation. Here, an order transition in an IL@MOF composite is discovered using CuBTC (copper benzene-1,3,5-tricarboxylate) and [EMIM][TFSI] (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide). This transition – absent for the bare MOF or IL – provides an extended super-cooling range and latent heat at a capacity similar to that of soft paraffins, in the temperature range of ≈220 °C. Structural analysis and in situ monitoring indicate an electrostatic interaction between the IL molecules and the Cu paddle-wheels, leading to a decrease in pore symmetry at low temperature. These interactions are reversibly released above the transition temperature, which reflects in a volume expansion of the MOF-IL composite.
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Jul 2024
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I15-1-X-ray Pair Distribution Function (XPDF)
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Ashleigh M.
Chester
,
Celia
Castillo-Blas
,
Roman
Sajzew
,
Bruno P.
Rodrigues
,
Giulio I.
Lampronti
,
Adam F.
Sapnik
,
Georgina P.
Robertson
,
Matjaž
Mazaj
,
Daniel J. M.
Irving
,
Lothar
Wondraczek
,
David A.
Keen
,
Thomas D.
Bennett
Open Access
Abstract: Here we describe the synthesis of a compositional series of metal–organic framework crystalline-inorganic glass composites (MOF-CIGCs) containing ZIF-8 and an inorganic phosphate glass, 20Na2O–10NaCl–70P2O5, to expand the library of host matrices for metal–organic frameworks. By careful selection of the inorganic glass component, a relatively high loading of ZIF-8 (70 wt%) was achieved, which is the active component of the composite. A Zn⋯O–P interfacial bond, previously identified in similar composites/hybrid blends, was suggested by analysis of the total scattering pair distribution function data. Additionally, CO2 and N2 sorption and variable-temperature PXRD experiments were performed to assess the composites’ properties.
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Jun 2024
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[26330]
Open Access
Abstract: We use a combination of X-ray pair distribution function (PDF) measurements, lattice dynamical calculations, and ab initio density functional theory (DFT) calculations to study the local structure and dynamics in various MPt(CN)6 Prussian blue analogues. In order to link directly the local distortions captured by the PDF with the lattice dynamics of this family, we develop and apply a new “interaction-space” PDF refinement approach. This approach yields effective harmonic force constants, from which the (experiment-derived) low-energy phonon dispersion relations can be approximated. Calculation of the corresponding Grüneisen parameters allows us to identify the key modes responsible for negative thermal expansion (NTE) as arising from correlated tilts of coordination octahedra. We compare our results against the phonon dispersion relations determined using DFT calculations, which identify the same NTE mechanism.
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May 2024
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I15-1-X-ray Pair Distribution Function (XPDF)
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Chumei
Ye
,
Giulio
Lampronti
,
Lauren N.
Mchugh
,
Celia
Castillo-Blas
,
Ayano
Kono
,
Celia
Chen
,
Georgina P.
Robertson
,
Liam A. V.
Nagle-Cocco
,
Weidong
Xu
,
Samuel D.
Stranks
,
Valentina
Martinez
,
Ivana
Brekalo
,
Bahar
Karadeniz
,
Krunoslav
Užarević
,
Wenlong
Xue
,
Pascal
Kolodzeiski
,
Chinmoy
Das
,
Philip
Chater
,
David A.
Keen
,
Sian E.
Dutton
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Hybrid organic–inorganic perovskites (HOIPs) occupy a prominent position in the field of materials chemistry due to their attractive optoelectronic properties. While extensive work has been done on the crystalline materials over the past decades, the newly reported glasses formed from HOIPs open up a new avenue for perovskite research with their unique structures and functionalities. Melt-quenching is the predominant route to glass formation; however, the absence of a stable liquid state prior to thermal decomposition precludes this method for most HOIPs. In this work, we describe the first mechanochemically-induced crystal-glass transformation of HOIPs as a rapid, green and efficient approach for producing glasses. The amorphous phase was formed from the crystalline phase within 10 minutes of ball-milling, and exhibited glass transition behaviour as evidenced by thermal analysis techniques. Time-resolved in situ ball-milling with synchrotron powder diffraction was employed to study the microstructural evolution of amorphisation, which showed that the crystallite size reaches a comminution limit before the amorphisation process is complete, indicating that energy may be further accumulated as crystal defects. Total scattering experiments revealed the limited short-range order of amorphous HOIPs, and their optical properties were studied by ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy.
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Apr 2024
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[34243]
Open Access
Abstract: In this work, we present a variable-temperature 23Na NMR and variable-temperature and variable-frequency electron paramagnetic resonance (EPR) analysis of the local structure of a layered P2 Na-ion battery cathode material, Na0.67[Mg0.28Mn0.72]O2 (NMMO). For the first time, we elucidate the superstructure in this material by using synchrotron X-ray diffraction and total neutron scattering and show that this superstructure is consistent with NMR and EPR spectra. To complement our experimental data, we carry out ab initio calculations of the quadrupolar and hyperfine 23Na NMR shifts, the Na+ ion hopping energy barriers, and the EPR g-tensors. We also describe an in-house simulation script for modeling the effects of ionic mobility on variable-temperature NMR spectra and use our simulations to interpret the experimental spectra, available upon request. We find long-zigzag-type Na ordering with two different types of Na sites, one with high mobility and the other with low mobility, and reconcile the tendency toward Na+/vacancy ordering to the preservation of local electroneutrality. The combined magnetic resonance methodology for studying local paramagnetic environments from the perspective of electron and nuclear spins will be useful for examining the local structures of materials for devices.
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Dec 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Haolai
Tian
,
Guanqun
Cai
,
Lei
Tan
,
He
Lin
,
Anthony E.
Phillips
,
Isaac
Abrahams
,
David A.
Keen
,
Dean S.
Keeble
,
Andy
Fiedler
,
Junrong
Zhang
,
Xiang Yang
Kong
,
Martin T.
Dove
Diamond Proposal Number(s):
[19378]
Open Access
Abstract: The lithium-ion conducting solid electrolyte Li7La3Zr2O12 has one crystalline phase that has the cubic garnet structure, and this phase has one of the highest room temperature lithium-ion conductivities of any oxide. Neutron and X-ray total scattering data, analysed by the Reverse Monte Carlo method, have been used to examine the distribution of lithium ions over a wide range of temperatures, and to explore aspects of the stability and flexibility of the basic oxide structure. We compare the results with those from supporting molecular dynamics simulations. Unlike previous work, our method requires no prior assumptions about the Li ion distribution. Using total scattering rather than solely Bragg scattering, we obtain much higher real-space resolution than previously available. The combination of X-ray and neutron scattering allows detailed characterisation of both the mobile and immobile sublattices. Only a small fraction of Li ions are mobile at any one time; diffusion occurs primarily by movement between Li2 sites via empty Li1 sites.
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Oct 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Celia
Castillo-Blas
,
Ashleigh M.
Chester
,
Ronan P.
Cosquer
,
Adam F.
Sapnik
,
Lucia
Corti
,
Roman
Sajzew
,
Bruno
Poletto-Rodrigues
,
Georgina P.
Robertson
,
Daniel J. M.
Irving
,
Lauren N.
Mchugh
,
Lothar
Wondraczek
,
Frédéric
Blanc
,
David A.
Keen
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[29957]
Open Access
Abstract: The interface within a composite is critically important for the chemical and physical properties of these materials. However, experimental structural studies of the interfacial regions within metal–organic framework (MOF) composites are extremely challenging. Here, we provide the first example of a new MOF composite family, i.e., using an inorganic glass matrix host in place of the commonly used organic polymers. Crucially, we also decipher atom–atom interactions at the interface. In particular, we dispersed a zeolitic imidazolate framework (ZIF-8) within a phosphate glass matrix and identified interactions at the interface using several different analysis methods of pair distribution function and multinuclear multidimensional magic angle spinning nuclear magnetic resonance spectroscopy. These demonstrated glass–ZIF atom–atom correlations. Additionally, carbon dioxide uptake and stability tests were also performed to check the increment of the surface area and the stability and durability of the material in different media. This opens up possibilities for creating new composites that include the intrinsic chemical properties of the constituent MOFs and inorganic glasses.
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Oct 2023
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I11-High Resolution Powder Diffraction
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Ashleigh M.
Chester
,
Celia
Castillo-Blas
,
Roman
Sajzew
,
Bruno
Poletto Rodrigues
,
Ruben
Mas Balleste
,
Alicia
Moya
,
Jessica E.
Snelson
,
Sean M.
Collins
,
Adam F.
Sapnik
,
Georgina P.
Robertson
,
Daniel J. M.
Irving
,
Lothar
Wondraczek
,
David A.
Keen
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Recently, increased attention has been focused on amorphous metal-organic frameworks (MOFs) and, more specifically, MOF glasses, the first new glass category discovered since the 1970s. In this work, we explore the fabrication of a compositional series of hybrid blends, the first example of blending a MOF and inorganic glass. We combine ZIF-62(Zn) glass and an inorganic glass, 30Na2O-70P2O5, in an effort to combine the chemical versatility of the MOF glass with the mechanical properties of the inorganic glass. We investigate the interfacial interactions between the two components using pair distribution function analysis and solid state NMR spectroscopy, and suggest potential interactions between the two phases. Thermal analysis of the blend samples indicated that they were less thermally stable than the starting materials, and had a Tg shifted relative to the pristine materials. Annular dark field scanning transmission electron microscopy tomography, X-ray energy dispersive spectroscopy (EDS), nanoindentation and 31P NMR all indicated close mixing of the two phases, suggesting that immiscible blends had formed.
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Sep 2023
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[31314]
Open Access
Abstract: Recent research on metal–organic frameworks (MOFs) has shown a shift from considering only the crystalline high-porosity phases to exploring their amorphous counterparts. Applying pressure to a crystalline MOF is a common method of amorphization, as MOFs contain large void spaces that can collapse, reducing the accessible surface area. This can be either a desired change or indeed an unwanted side effect of the application of pressure. In either case, understanding the MOF’s pressure response is extremely important. Three such MOFs with varying pore sizes (UiO-66, MOF-808, and NU-1000) were investigated using in situ high-pressure X-ray diffraction and Raman spectroscopy. Partial crystallinity was observed in all three MOFs above 10 GPa, along with some recovery of crystallinity on return to ambient conditions if the frameworks were not compressed above thresholds of 13.3, 14.2, and 12.3 GPa for UiO-66, MOF-808, and NU-1000, respectively. This threshold was marked by an unexpected increase in one or more lattice parameters with pressure in all MOFs. Comparison of compressibility between MOFs suggests penetration of the pressure-transmitting oil into MOF-808 and NU-1000. The survival of some crystallinity above 10 GPa in all of these MOFs despite their differing pore sizes and extents of oil penetration demonstrates the importance of high-pressure characterization of known structures.
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Jun 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Alice M.
Bumstead
,
Celia
Castillo-Blas
,
Ignas
Pakamore
,
Michael F.
Thorne
,
Adam F.
Sapnik
,
Ashleigh M.
Chester
,
Georgina
Robertson
,
Daniel J. M.
Irving
,
Philip A.
Chater
,
David A.
Keen
,
Ross S.
Forgan
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: The chemistries that can be incorporated within melt-quenched zeolitic imidazolate framework (ZIF) glasses are currently limited. Here we describe the preparation of a previously unknown purine-containing ZIF which we name ZIF-UC-7. We find that it melts and forms a glass at one of the lowest temperatures reported for 3D hybrid frameworks.
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Dec 2022
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