I15-1-X-ray Pair Distribution Function (XPDF)
I21-Resonant Inelastic X-ray Scattering (RIXS)
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Diamond Proposal Number(s):
[35064, 39285, 40912]
Open Access
Abstract: Li-rich disordered rocksalts are promising next-generation cathode materials for Li-ion batteries. Recent reports have shown it is also possible to obtain Na-rich disordered rocksalts, however, it is currently poorly understood how the knowledge of the structural and redox chemistry translates from the Li-rich to the Na-rich analogs. Here, the properties of Li2MnO2F and Na2MnO2F are compared, which have different ion sizes (Li+ = 0.76 vs Na+ = 1.02 Å) but the same disordered rocksalt structure and stoichiometry. It is found that Na2MnO2F exhibits lower voltage Mn- and O-redox couples, opening access to a wider compositional range within the same voltage limits. Furthermore, the intercalation mechanism switches from predominantly single-phase solid solution behavior in Li2MnO2F to a two-phase transition in Na2MnO2F, accompanied by a greater decrease in the average Mn─O/F bond length. Li2MnO2F retains its long-range disordered rocksalt structure throughout the first cycle. In contrast, Na2MnO2F becomes completely amorphous during charge and develops a local structure characteristic of a post-spinel. This amorphization is partially reversible on discharge. The results show how the ion intercalation behavior of disordered rocksalts differs dramatically when changing from Li- to Na-ions and offers routes to control the electrochemical properties of these high-energy-density cathodes.
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May 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[37860]
Open Access
Abstract: Supramolecular deep eutectic solvents (SUPRADESs), formed by combining cyclodextrins (CDs) with hydrogen bond donors, enhance solvation efficiency while retaining CD inclusion capabilities. This study presents the first detailed structural analysis of a SUPRADES composed of β-cyclodextrin (β-CD) and lactic acid (LA) (1:30 M ratio) using Molecular Dynamics simulations and X-ray scattering. Results reveal a well-dispersed system where LA molecules form stabilizing sheaths around isolated β-CDs, preventing coalescence through optimized hydrogen bonding and dispersive interactions. The SUPRADES significantly improved solubilisation and retention of water-insoluble trans-anethole (AN), demonstrating strong absorption capacity. While β-CD encapsulation of AN was limited, 2D ROESY NMR confirmed inclusion complex formation. These findings highlight the SUPRADES's unique microstructure and its potential as a sustainable, eco-friendly solvent for volatile organic compound (VOC) applications, offering insights for future green solvent design.
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May 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Wen-Long
Xue
,
Alexander
Klein
,
Mounir
El Skafi
,
Jan-Benedikt
Weiss
,
Felix
Egger
,
Hui
Ding
,
Suresh K.
Vasa
,
Christian
Liebscher
,
Mirijam
Zobel
,
Rasmus
Linser
,
Jin-Chong
Tan
,
Sebastian
Henke
Diamond Proposal Number(s):
[36120]
Abstract: Metal-organic frameworks (MOFs) are versatile materials with tunable properties and broad applications. Here, we report the first cadmium-based zeolitic imidazolate framework (ZIF) glass, prepared by melt-quenching sub-micrometer-sized Cd(im)2 particles (im– = imidazolate) obtained via mechanochemical synthesis. This route increases defect density and reduces crystallite domain size, lowering the melting temperature from 461 °C (for larger solution-synthesized microcrystals) to 455 °C, thereby mitigating thermal decomposition during melting. Crystalline Cd(im)2 adopts a two-fold interpenetrated diamondoid (dia-c) topology, assembled from tetrahedral Cd2+ centers and im– linkers. Rapid cooling of the Cd(im)2 melt yields a monolithic glass with a glass transition temperature (Tg) of 175 °C. Structural analysis confirms that short-range connectivity within individual networks is maintained, whereas interactions between the interpenetrated networks are disrupted in the glass. Upon reheating, partial recrystallization produces a single-component glass–ceramic with enhanced mechanical properties, an unprecedented behavior in melt-quenched ZIF glasses. Investigations of thermal parameters (cooling rates) and partial linker substitution reveal strategies for tuning the phase behavior of both glass and glass–ceramic. These findings extend ZIF glass systems to second-row transition metal ions and underscore mechanochemical synthesis as a tool for tailoring the thermal properties of MOFs. This dual-phase functionality, combining glassy and crystalline domains of identical composition within a single material, offers potential for applications in thermal energy storage, phase change memory, and optics.
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Apr 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[29957]
Open Access
Abstract: We report the solvent-free synthesis of a crystalline heterometallic imidazolate derivative with formula [Fe1Zn2(im)6(Him)2], designated MUV-25, incorporating both iron and zinc. The structure imposes strict positional constraints on the metal centres due to the lattice containing distinct geometric coordination sites, tetrahedral and octahedral. As a consequence, each metal is exclusively directed to its specific coordination site, ensuring precise spatial organization within the lattice. Atom locations were meticulously monitored utilizing X-ray diffraction (single crystal and total scattering) and XAS techniques, demonstrating that the tetrahedral sites are occupied exclusively by zinc, and the octahedral sites are occupied by iron. This combination of metal centres results, upon heating, in a structural phase transformation to the zni topology at a very low temperature. Further heating causes the melting of the solid, yielding a heterometallic MOF-derived glass. The methodology lays the groundwork for tailoring crystalline structures to advance the development of novel materials capable of melting and forming glasses upon cooling.
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Mar 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Celia
Castillo-Blas
,
Montaña J.
García
,
Ashleigh M.
Chester
,
Matjaž
Mazaj
,
Shaoliang
Guan
,
Georgina P.
Robertson
,
Ayano
Kono
,
James M. A.
Steele
,
Luis
León-Alcaide
,
Bruno
Poletto-Rodrigues
,
Philip A.
Chater
,
Silvia
Cabrera
,
Andraž
Krajnc
,
Lothar
Wondraczek
,
David A.
Keen
,
Jose
Alemán
,
Thomas
Bennett
Diamond Proposal Number(s):
[29957]
Open Access
Abstract: Metal–organic framework (MOF) composites are proposed as solutions to the mechanical instability of pure MOF materials. Here, we present a new compositional series of recently discovered MOF–crystalline inorganic glass composites. In this case, formed by the combination of a photocatalytic titanium MOF (MIL-125-NH2) and a phosphate-based glass (20%Na2O–10%Na2SO4–70%P2O5). This new family of composites has been synthesized and characterized using powder X-ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and X-ray total scattering. Through analysis of the pair distribution function extracted from X-ray total scattering data, the atom–atom interactions at the MOF–glass interface are described. Nitrogen and carbon dioxide isotherms demonstrate good surface area values despite the pelletization and mixing of the MOF with a dense inorganic glass. The catalytic activity of these materials was investigated in the photooxidation of amines to imines, showing the retention of the photocatalytic effectiveness of the parent pristine MOF.
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Mar 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[34748]
Abstract: We present a structural characterization of a low-transition-temperature mixture (LTTM), consisting of thymol and carvacrol, at an equimolar ratio. Carvacrol and thymol are natural regioisomers of terpenes. When combined at an equimolar ratio, they form a liquid mixture at room temperature, with supercooling capability and glass transition at ca. 210 K. Using small- and wide-angle X-ray scattering and molecular dynamics, we describe the structural complexity within this system. X-ray scattering reveals a low-Q peak at around 0.6 Å–1, indicating the existence of mesoscale structural heterogeneities, likely related to the segregation of polar moieties engaged in hydrogen bond (HB) interactions within an aromatic, apolar matrix. These polar interactions are predominantly a result of HBs involving thymol as the HB donor species. The liquid structure is also driven by O–H···π interactions, prevalently due to the ability of the carvacrol π-site to engage in this type of weak interaction as a HB acceptor. Besides, dispersive interactions affect the local arrangement of molecules, with a propensity of carvacrol rings to orient their first neighbors with a perpendicular orientation, while thymol tends to induce a closer approach of other thymol molecules with a preferential parallel alignment. Overall, we observed a complex structural arrangement driven by the interplay of both conventional and weak hydrogen bond interactions, with the aromatic nature of the compounds playing a pivotal role in shaping the system’s architecture. Carvacrol and thymol, despite being very similar compounds, are characterized by distinctly different behavior in terms of the interactions they engage in with their neighbors, likely due to the different steric hindrance experienced by their hydroxyl groups, which are close to either a small methyl or a bulky isopropyl group, respectively. Such observations can provide useful hints to develop new solvents with tailored properties.
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Mar 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Shichun
Li
,
Chao
Ma
,
Jingwei
Hou
,
Shuwen
Yu
,
Aibing
Chen
,
Juan
Du
,
Philip A.
Chater
,
Dean S.
Keeble
,
Zhihua
Qiao
,
Chongli
Zhong
,
David A.
Keen
,
Yu
Liu
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Crystalline metal-organic frameworks (MOFs) exhibit enormous potential application in gas separation, thanks to their highly porous structures and precise pore size distributions. Nevertheless, the inherent limitations in mechanical stability of crystalline MOFs cause challenges in processing MOF powders into bulky structures, particularly for membrane filtrations. Melt-quenched MOF glasses boast excellent processability due to liquid-like properties. However, the melting process diminishes the inherent porosity, leading to reduced gas adsorption capacities and lower gas diffusion coefficients. In this work, we demonstrated that enhancing the porosity of MOF glasses is achievable through topological engineering on the crystalline precursors. Crystalline zeolitic imidazolate frameworks (ZIFs) with large 12-membered rings pores, including AFI and CAN topology, were synthesized by using both structure-directing agents and mixed organic ligands. The large pores are partially preserved in the melt-quenched glass as evidenced by high-pressure CO2 absorption at 3000 kPa. The agAFI-[Zn(Im)1.68(bIm)0.32] glass was then fabricated into self-supported membranes, which shows high gas separation performance, for example, CO2 permeance of 3.7 × 104 GPU with a CO2/N2 selectivity of 14.8.
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Feb 2025
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I11-High Resolution Powder Diffraction
I15-1-X-ray Pair Distribution Function (XPDF)
I15-Extreme Conditions
I20-EDE-Energy Dispersive EXAFS (EDE)
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Diamond Proposal Number(s):
[31314, 31898, 20038, 29957, 30178]
Abstract: Metal-organic frameworks (MOFs) are a versatile class of hybrid inorganic-organic materials known for their adjustable chemical and physical properties, as well as their exceptional porosity. These characteristics render MOFs particularly valuable for applications requiring extensive surface areas, such as gas storage and catalysis. Despite being advantageous in many applications, the high porosity and specific bonding characteristics of crystalline MOFs can, however, make them susceptible to pore collapse and amorphisation under pressure. This limits the practical effectiveness of MOFs in their most commonly synthesised form of crystalline powders, as large-scale production and shaping of powders for industrial use often involves pressure and heating.
This thesis examines how a range of MOFs behave under various high pressure and high pressure-temperature conditions to examine both their amorphisation mechanisms and amorphous phases formed. The MOFs were selected to fall within two groups: zirconium-based (UiO-66, MOF-808 and NU-1000) and zinc-based (ZIF-8, ZIF-4 and ZIF-62). The methods chosen for investigations were hydrostatic compression, non-hydrostatic compression, and ball-milling, as they are all used for industrial processing of powders: The former two are methods for shaping, and the latter for mixing. Hydrostatic compression of these MOFs is investigated in depth through in situ high pressure-temperature crystallographic and spectroscopic measurements, allowing real-time analysis on the MOFs’ collapse mechanisms. Both groups display partially reversible amorphisation under hydrostatic compression to certain pressures, indicating a displacive amorphisation transition into an amorphous phase topologically similar to the crystalline. Penetration of the pressure-transmitting media into the framework’s pores was also indicated in each MOF, with clear negative volume compressibility shown in the zinc-based MOFs.
Ex situ investigations into non-hydrostatic compression then introduce the effect of shear stress so its effect on the MOFs can be highlighted, where the two groups demonstrate quite different behaviour attributed to differences in the connectivity of their inorganic components. Ball-milling is finally examined as a non-compression form of amorphisation with a high shear component. In both shear-based pressure states, decoordination of the organic components from the inorganic is seen as a driving factor of amorphisation. Understanding the collapse mechanisms and resultant amorphous phases from various amorphisation methods in these MOFs gives insight into trends in mechanical properties and stability within this class of materials, and is essential for the future industrialisation of MOFs.
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Jan 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Hengtong
Bu
,
Hengwei
Luan
,
Jingyi
Kang
,
Jili
Jia
,
Wenhui
Guo
,
Yunshuai
Su
,
Huaping
Ding
,
Hsiang-Shun
Chang
,
Ranbin
Wang
,
You
Wu
,
Lingxiang
Shi
,
Pan
Gong
,
Qiaoshi
Zeng
,
Yang
Shao
,
Kefu
Yao
Open Access
Abstract: As a medium to understand the nature of glass transition, ultrastable glasses have garnered increasing attention for their significance in fundamental science and technological applications. Most studies have produced ultrastable glasses through a surface-controlled process using physical vapor deposition. Here, we demonstrate an approach to accessing ultrastable glasses via the glass-to-glass transition, a bulk transformation that is inherently free from size constraints and anisotropy. The resulting ultrastable glass exhibits a significantly enhanced density (improved by 2.3%), along with high thermodynamic, kinetic, and mechanical stability. Furthermore, we propose that this method of accessing ultrastable glasses is general for metallic glasses, based on the examination of the competitive relationship between the glass-to-glass transition and crystallization. This strategy is expected to facilitate the proliferation of the ultrastable glass family, helping to resolve the instability issues of glass materials and devices and deepen our understanding of glasses and the glass transition.
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Jan 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Bikash Kumar
Shaw
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Lucia
Corti
,
Joshua M.
Tuffnell
,
Celia
Castillo-Blas
,
Patrick
Schlachta
,
Georgina P.
Robertson
,
Lauren
Mchugh
,
Adam F.
Sapnik
,
Sebastian A.
Hallweger
,
Philip A.
Chater
,
Gregor
Kieslich
,
David A.
Keen
,
Sian E.
Dutton
,
Frédéric
Blanc
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: ABX3-type hybrid organic–inorganic structures have recently emerged as a new class of meltable materials. Here, by the use of phenylphosphonium derivatives as A cation, we study liquid- and glass-forming behavior of a new family of hybrid structures, (RPh3P)[Mn(dca)3] (R = Me, Et, Ph; dca = dicyanamide). These new compounds melt at 196–237 °C (Tm) and then vitrify upon cooling to room temperature, forming glasses. In situ glass formation of this new family of materials was probed on a large scale using a variable-temperature PXRD experiment. Structure analyses of the crystalline and the glasses were carried out by solid-state nuclear magnetic resonance spectroscopy and synchrotron X-ray total scattering techniques for using the pair distribution function. The mechanical properties of the glasses produced were evaluated showing promising durability. Thermal and electrical conductivities showed low thermal conductivities (κ ∼ 0.07–0.09 W m–1 K–1) and moderate electrical conductivities (σ ∼ 10–4–10–6 S m–1) at room temperature, suggesting that by the precise control of the A cation, we can tune meltable hybrid structures from moderate conductors to efficient thermal insulators. Our results raise attention on the practical use of this new hybrid material in applications including, e.g., photovoltaic devices to prevent light-deposited heat (owing to low κRT), energy harvesting thermoelectric, etc., and advance the structure–property understanding.
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Dec 2024
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