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

Instruments / Technical Area	Publication Details	Published
I19-Small Molecule Single Crystal Diffraction	Materials discovery and design limits in MDABCO perovskites Samuel D. Gale , Harry J. Lloyd , Louise Male , Mark R. Warren , Lucy K. Saunders , Paul A. Anderson , Hamish H.-M. Yeung Crystengcomm 91 DOI: 10.1039/D2CE00848C Diamond Proposal Number(s): [26118] Open Access Show Abstract ▼ Abstract: We report the structures of three new materials in the MDABCO-based perovskite family. Analysis of the Goldschmidt tolerance factor and octahedral factor enable us to propose compositional limits for pseudo-cubic perovskite phase formation and suggest directions for further materials discovery in this family of new ferroelectrics.	Aug 2022
I19-Small Molecule Single Crystal Diffraction	An electric field cell for performing in situ single-crystal synchrotron X-ray diffraction Lucy K. Saunders , Hamish H.-M. Yeung , Mark Warren , Peter Smith , Stuart Gurney , Stephen F. Dodsworth , Inigo Vitorica-Yrezabal , Adrian Wilcox , Paul V. Hathaway , Geoff Preece , Paul Roberts , Sarah A. Barnett , David R. Allan Journal Of Applied Crystallography 54 DOI: 10.1107/S1600576721007469 Diamond Proposal Number(s): [19670, 22964] Open Access Show Abstract ▼ Abstract: With the recent increase in research into ferroelectric, anti-ferroelectric and piezoelectric materials, studying the solid-state properties in situ under applied electric fields is vital in understanding the underlying processes. Where this behaviour is the result of atomic displacements, crystallographic insight has an important role. This work presents a sample environment designed to apply an electric field to single-crystal samples in situ on the small-molecule single-crystal diffraction beamline I19, Diamond Light Source (UK). The configuration and operation of the cell is described as well as its application to studies of a proton-transfer colour-change material.	Oct 2021
I19-Small Molecule Single Crystal Diffraction	High-pressure crystal structure and unusual magnetoresistance of a single-component molecular conductor [Pd(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) Hengbo Cui , Hamish H.-M. Yeung , Yoshitaka Kawasugi , Takaaki Minamidate , Lucy K. Saunders , Reizo Kato Crystals 11 DOI: 10.3390/cryst11050534 Diamond Proposal Number(s): [20934] Open Access Show Abstract ▼ Abstract: A single-component molecular crystal [Pd(dddt)2] has been shown to exhibit almost temperature-independent resistivity under high pressure, leading theoretical studies to propose it as a three-dimensional (3D) Dirac electron system. To obtain more experimental information about the high-pressure electronic states, detailed resistivity measurements were performed, which show temperature-independent behavior at 13 GPa and then an upturn in the low temperature region at higher pressures. High-pressure single-crystal structure analysis was also performed for the first time, revealing the presence of pressure-induced structural disorder, which is possibly related to the changes in resistivity in the higher-pressure region. Calculations based on the disordered structure reveal that the Dirac cone state and semiconducting state coexist, indicating that the electronic state at high pressure is not a simple Dirac electron system as previously believed. Finally, the first measurements of magnetoresistance on [Pd(dddt)2] under high pressure are reported, revealing unusual behavior that seems to originate from the Dirac electron state.	May 2021
I11-High Resolution Powder Diffraction I12-JEEP: Joint Engineering, Environmental and Processing	Single-step synthesis and interface tuning of core–shell metal–organic framework nanoparticles Kieran W. P. Orr , Sean M. Collins , Emily M. Reynolds , Frank Nightingale , Hanna L. B. Bostroem , Simon J. Cassidy , Daniel M. Dawson , Sharon E. Ashbrook , Oxana Magdysyuk , Paul A. Midgley , Andrew L. Goodwin , Hamish H.-M. Yeung Chemical Science 13 DOI: 10.1039/D0SC03940C Diamond Proposal Number(s): [20946, 18786] Open Access Show Abstract ▼ Abstract: Control over the spatial distribution of components in metal–organic frameworks has potential to unlock improved performance and new behaviour in separations, sensing and catalysis. We report an unprecedented single-step synthesis of multi-component metal–organic framework (MOF) nanoparticles based on the canonical ZIF-8 (Zn) system and its Cd analogue, which form with a core–shell structure whose internal interface can be systematically tuned. We use scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and a new composition gradient model to fit high-resolution X-ray diffraction data to show how core–shell composition and interface characteristics are intricately controlled by synthesis temperature and reaction composition. Particle formation is investigated by in situ X-ray diffraction, which reveals that the spatial distribution of components evolves with time and is determined by the interplay of phase stability, crystallisation kinetics and diffusion. This work opens up new possibilities for the control and characterisation of functionality, component distribution and interfaces in MOF-based materials.	Feb 2021
I19-Small Molecule Single Crystal Diffraction	Electronic structure of a single-component molecular conductor [Pd(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) under high pressure Reizo Kato , Hengbo Cui , Takaaki Minamidate , Hamish H.-M. Yeung , Yoshikazu Suzumura Journal Of The Physical Society Of Japan 89 DOI: 10.7566/JPSJ.89.124706 Diamond Proposal Number(s): [20934] Show Abstract ▼ Abstract: We examined the high-pressure electronic structure of a single-component molecular conductor [Pd(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) at room temperature, on the basis of the crystal structure determined by single-crystal synchrotron X-ray diffraction measurements at 5.9 GPa. The monoclinic unit cell contains four molecules that form two crystallographically independent molecular layers. A tight-binding model of an 8 × 8 matrix Hamiltonian gives an electronic structure as a Dirac electron system. The Dirac point describes a loop within the first Brillouin zone, and a nodal line semimetal is obtained. The noticeable property of the Dirac cone with a linear dispersion is shown by calculating the density of states (DOS). The Dirac cone in this system is associated with the crossing of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) bands, which originates from the direct interaction between different molecular layers. This is a newly found mechanism in addition to the indirect interaction [J. Phys. Soc. Jpn. 86, 064705 (2017)]. The Dirac points emerge as a line when the HOMO and LUMO bands meet on the surface and the HOMO–LUMO couplings are absent. Such a mechanism is verified using a reduced model of a 4 × 4 matrix Hamiltonian. The deviation of the band energy (δE) at the Dirac point from the Fermi level is very small (δE < 0.4 meV). The nodal line is examined by calculating the parity of the occupied band eigenstates at time reversal invariant momentum (TRIM), which shows that the topological number is 1.	Dec 2020
I12-JEEP: Joint Engineering, Environmental and Processing	Exploiting in-situ NMR to monitor the formation of a metal-organic framework Corey L. Jones , Colan E. Hughes , Hamish H.-M. Yeung , Alison Paul , Kenneth D. M. Harris , Timothy L. Easun Chemical Science DOI: 10.1039/D0SC04892E Diamond Proposal Number(s): [16450] Open Access Show Abstract ▼ Abstract: The formation processes of metal–organic frameworks are becoming more widely researched using in situ techniques, although there remains a scarcity of NMR studies in this field. In this work, the synthesis of framework MFM-500(Ni) has been investigated using an in situ NMR strategy that provides information on the time-evolution of the reaction and crystallization process. In our in situ NMR study of MFM-500(Ni) formation, liquid-phase 1H NMR data recorded as a function of time at fixed temperatures (between 60 and 100 °C) afford qualitative information on the solution-phase processes and quantitative information on the kinetics of crystallization, allowing the activation energies for nucleation (61.4 ± 9.7 kJ mol−1) and growth (72.9 ± 8.6 kJ mol−1) to be determined. Ex situ small-angle X-ray scattering studies (at 80 °C) provide complementary nanoscale information on the rapid self-assembly prior to MOF crystallization and in situ powder X-ray diffraction confirms that the only crystalline phase present during the reaction (at 90 °C) is phase-pure MFM-500(Ni). This work demonstrates that in situ NMR experiments can shed new light on MOF synthesis, opening up the technique to provide better understanding of how MOFs are formed.	Nov 2020
B22-Multimode InfraRed imaging And Microspectroscopy	Guest‐tunable dielectric sensing using a single crystal of HKUST‐1 Arun S. Babal , Abhijeet K. Chaudhari , Hamish H.-M. Yeung , Jin-Chong Tan Advanced Materials Interfaces 7 DOI: 10.1002/admi.202000408 Open Access Show Abstract ▼ Abstract: There is rising interest on low‐k dielectric materials based on porous metal–organic frameworks (MOFs) for improved electrical insulation in microelectronics. Herein, the concept of MOF dielectric sensor built from a single crystal of HKUST‐1 is demonstrated. Guest encapsulation effects of polar and non‐polar molecules are studied, by monitoring the transient dielectric response and AC conductivity of the crystal exposed to different vapors (water, iodine, methanol, and ethanol). The dielectric properties are measured along the <100> crystal direction in the frequency range of 100 Hz to 2 MHz. The dielectric data show the efficacy of MOF dielectric sensor for discriminating the guest analytes. The time‐dependent transient response reveals dynamics of the molecular inclusion and exclusion processes in the nanoscale pores. Since dielectric response is ubiquitous to all MOF materials (unlike DC conductivity and fluorescence), the results demonstrate the potential of dielectric MOF sensors compared to resistive sensors and luminescence‐based approaches.	Jul 2020
I19-Small Molecule Single Crystal Diffraction	High pressure crystal structure and electrical properties of a single component molecular crystal [Ni(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) Hengbo Cui , Takao Tsumuraya , Hamish H.-M. Yeung , Chloe S. Coates , Mark R. Warren , Reizo Kato Molecules 24 DOI: 10.3390/molecules24101843 Diamond Proposal Number(s): [15000] Open Access Show Abstract ▼ Abstract: Single-component molecular conductors form an important class of materials showing exotic quantum phenomena, owing to the range of behavior they exhibit under physical stimuli. We report the effect of high pressure on the electrical properties and crystal structure of the single-component crystal [Ni(dddt)2] (where dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate). The system is isoelectronic and isostructural with [Pd(dddt)2], which is the first example of a single-component molecular crystal that exhibits nodal line semimetallic behavior under high pressure. Systematic high pressure four-probe electrical resistivity measurements were performed up to 21.6 GPa, using a Diamond Anvil Cell (DAC), and high pressure single crystal synchrotron X-ray diffraction was performed up to 11.2 GPa. We found that [Ni(dddt)2] initially exhibits a decrease of resistivity upon increasing pressure but, unlike [Pd(dddt)2], it shows pressure-independent semiconductivity above 9.5 GPa. This correlates with decreasing changes in the unit cell parameters and intermolecular interactions, most notably the π-π stacking distance within chains of [Ni(dddt)2] molecules. Using first-principles density functional theory (DFT) calculations, based on the experimentally-determined crystal structures, we confirm that the band gap decreases with increasing pressure. Thus, we have been able to rationalize the electrical behavior of [Ni(dddt)2] in the pressure-dependent regime, and suggest possible explanations for its pressure-independent behavior at higher pressures.	May 2019
I12-JEEP: Joint Engineering, Environmental and Processing	Control of metal-organic framework crystallization by metastable intermediate pre-equilibrium species Hamish Yeung , Adam F. Sapnik , Felicity Massingberd-Mundy , Michael W. Gaultois , Yue Wu , Duncan X. Fraser , Sebastian Henke , Roman Pallach , Niclas Heidenreich , Oxana Magdysyuk , Nghia T. Vo , Andrew L. Goodwin Angewandte Chemie International Edition DOI: 10.1002/anie.201810039 Diamond Proposal Number(s): [16354, 16450] Show Abstract ▼ Abstract: There is an increasingly large amount of interest in metal‐organic frameworks (MOFs) for a variety of applications, from gas sensing and separations to electronics and catalysis. Their exciting properties arise from their modular architectures, which self‐assemble from different combinations of metal‐based and organic building units. However, the exact mechanisms by which they crystallize remain poorly understood, thus limiting any realisation of real “structure by design”. We report important new insight into MOF formation, gained using in situ X‐ray diffraction, pH and turbidity measurements to uncover for the first time the evolution of metastable intermediate species in the canonical zeolitic imidazolate framework system, ZIF‐8. We reveal that the intermediate species exist in a dynamic pre‐equilibrium prior to network assembly and, depending on the reactant concentrations and the progress of reaction, the pre‐equilibrium can be made to favour under‐ or over‐coordinated Zn‐imidazolate species, thus accelerating or inhibiting crystallization, respectively. We thereby find that concentration can be effectively used as a synthetic handle to directly control particle size, with great implications for industrial scale‐up and gas sorption applications. These finding enables us to rationalise the apparent contradictions between previous studies of ZIF‐8 and, importantly, opens up new opportunities for the control of crystallization in network solids more generally, from the design of local structure to assembly of particles with precise dimensions.	Nov 2018
I11-High Resolution Powder Diffraction	Compositional inhomogeneity and tuneable thermal expansion in mixed-metal ZIF-8 analogues Adam F. Sapnik , Harry S. Geddes , Emily M. Reynolds , Hamish H.-M. Yeung , Andrew L. Goodwin Chemical Communications 13 DOI: 10.1039/C8CC04172E Diamond Proposal Number(s): [13284] Show Abstract ▼ Abstract: We study the structural and thermomechanical effects of cation substitution in the compositional family of metal–organic frameworks Zn1−xCdx(mIm)2 (HmIm = 2-methylimidazole). We find complete miscibility for all compositions x, with evidence of inhomogeneous distributions of Cd and Zn that in turn affect framework aperture characteristics. Using variable-temperature X-ray powder diffraction measurements, we show that Cd substitution drives a threefold reduction in the magnitude of thermal expansion behaviour. We interpret this effect in terms of an increased density of negative thermal expansion modes in the more flexible Cd-rich frameworks.	Aug 2018

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