A5046929050- X-ray Diffraction in Crystallography
- Metal-Organic Frameworks: Synthesis and Applications
- High-pressure geophysics and materials
- Glass properties and applications
- Advanced Condensed Matter Physics
- Solid-state spectroscopy and crystallography
- Magnetism in coordination complexes
- Nuclear Physics and Applications
- Lanthanide and Transition Metal Complexes
- Thermal Expansion and Ionic Conductivity
- Crystallography and molecular interactions
- Crystal Structures and Properties
- Inorganic Fluorides and Related Compounds
- Magnetic and transport properties of perovskites and related materials
- Pigment Synthesis and Properties
- Zeolite Catalysis and Synthesis
- Ferroelectric and Piezoelectric Materials
- Advanced Battery Materials and Technologies
- Enzyme Structure and Function
- Luminescence Properties of Advanced Materials
- Perovskite Materials and Applications
- Advanced NMR Techniques and Applications
- Machine Learning in Materials Science
- Physics of Superconductivity and Magnetism
- Inorganic Chemistry and Materials
Rutherford Appleton Laboratory
2016-2025
ISIS Neutron and Muon Source
2017-2025
Science and Technology Facilities Council
2013-2022
University of Oxford
2005-2021
Research Complex at Harwell
2006-2021
Didcot Community Hospital
2015-2021
Queen Mary University of London
2019
University of Warwick
2019
Oxfam
2017
Berkshire Buckinghamshire and Oxfordshire Wildlife Trust
2014
Total scattering, an increasingly important crystallographic research area, is defined theoretically in terms of correlation functions. Different researchers use different definitions for these functions, frequently leading to confusion the literature. Here, a consistent set equations total-scattering functions are developed and explicitly compared with other, often encountered, definitions. It hoped that this will lead increased transparency newcomers field total scattering.
We show that silver(I) hexacyanocobaltate(III), Ag3[Co(CN)6], exhibits positive and negative thermal expansion an order of magnitude greater than seen in other crystalline materials. This framework material expands along one set directions at a rate comparable to the most weakly bound solids known. By flexing like lattice fencing, couples this contraction perpendicular direction. gives is 14 times larger ZrW2O8. Density functional theory calculations quantify both low energy associated with...
A new approach to the reverse Monte Carlo analysis of total scattering data from polycrystalline materials is presented. The essential feature incorporation an explicit Bragg peaks using a profile refinement, taking account instrument resolution function. Other features including fitting magnetic materials, modelling lattice site disorder and restraint constraint options. method demonstrated by brief review studies carried out during its development. program RMCProfile represents significant...
Crystalline solids dominate the field of metal–organic frameworks (MOFs), with access to liquid and glass states matter usually prohibited by relatively low temperatures thermal decomposition. In this work, we give due consideration framework chemistry topology expand phenomenon melting 3D MOFs, linking crystal temperature kinetic fragility glass-forming liquids. Here show that can be lowered altering crystalline MOF state, which provides a route facilitate other MOFs. The glasses formed...
We show that ZIF-4, a metal-organic framework (MOF) with zeolitic structure, undergoes crystal--amorphous transition on heating to 300 $^\circ$C. The amorphous form, which we term a-ZIF, is recoverable ambient conditions or may be converted dense crystalline phase of the same composition by 400 Neutron and X-ray total scattering data collected during amorphization process are used as basis for reverse Monte Carlo refinement an atomistic model structure a-ZIF. best understood in terms...
The ability of metal-organic frameworks (MOFs) to gelate under specific synthetic conditions opens up new opportunities in the preparation and shaping hierarchically porous MOF monoliths, which could be directly implemented for catalytic adsorptive applications. In this work, we present first examples xero- or aerogel monoliths consisting solely nanoparticles several prototypical Zr4+-based MOFs: UiO-66-X (X = H, NH2, NO2, (OH)2), UiO-67, MOF-801, MOF-808 NU-1000. High reactant water...
To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In contrast, high internal surface areas are readily achieved in crystalline such as metal-organic frameworks (MOFs). It has recently discovered that a new family melt quenched can be produced from MOFs, though they thus far lacked the accessible intrinsic porosity their precursors. Here, we report first...
Hybrid glasses from melt-quenched metal-organic frameworks (MOFs) have been emerging as a new class of materials, which combine the functional properties crystalline MOFs with processability glasses. However, only handful are meltable. Porosity and metal-linker interaction strength both identified crucial parameters in trade-off between thermal decomposition organic linker and, more desirably, melting. For example, inability prototypical zeolitic imidazolate framework (ZIF) ZIF-8 to melt, is...
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 mechanical stability of crystalline MOFs cause challenges processing MOF powders into bulky structures, particularly for membrane filtrations. Melt-quenched glasses boast excellent processability due liquid-like properties. However, melting process diminishes porosity, leading...
Silver(I) hexacyanocobaltate(III), Ag 3 [Co(CN) 6 ], shows a large negative linear compressibility (NLC, expansion under hydrostatic pressure) at ambient temperature all pressures up to our experimental limit of 7.65(2) GPa. This behavior is qualitatively unaffected by transition 0.19 GPa new phase ]-II, whose structure reported here. The high-pressure also anisotropic thermal with uniaxial (NTE, on cooling). In both phases, the NLC/NTE effect arises as rapid compression/contraction layers...
The structural changes within the copper(I) halides induced by hydrostatic pressure have been investigated using powder neutron-diffraction technique. expected transition from ambient zinc-blende structure with tetrahedral coordination to octahedrally coordinated rocksalt is observed in both CuCl and CuBr. No phase CuI, presumably due limited maximum of our apparatus (\ensuremath{\sim}10 GPa). lower symmetry phases which occur as intermediate structures between studied detail. CuI undergo...
We report the reversible pressure-induced amorphization of a zeolitic imidazolate framework (ZIF-4, [Zn(Im)(2)]). This occurs irrespective pore occupancy and takes place via novel high pressure phase (ZIF-4-I) when solvent molecules are present in pores. A significant reduction bulk modulus upon evacuation is also observed for both ZIF-4 ZIF-4-I.
A fast and efficient mechanosynthesis (ball-milling) method of preparing amorphous zeolitic imidazolate frameworks (ZIFs) from different starting materials is discussed. Using X-ray total scattering, N(2) sorption analysis, gas pycnometry, these are indistinguishable one another temperature-amorphized ZIFs. Gas analysis also confirms that they nonporous once formed, in contrast to activated ZIF-4, which displays interesting gate-opening behavior. Nanoparticles a prototypical nanoporous...
Abstract The I 2 ‐sorption and ‐retention properties of several existing zeolitic imidazolate frameworks (ZIF‐4, ‐8, ‐69) a novel framework, ZIF‐mnIm ([Zn(mnIm) ]; mnIm=4‐methyl‐5‐nitroimidazolate), have been characterised using microanalysis, thermogravimetric analysis X‐ray diffraction. topologically identical ZIF‐8 ([Zn(mIm) mIm=2‐methylimidazolate) display similar sorption abilities, though strikingly different guest‐retention behaviour upon heating. We discover that this guest retention...
The structural behavior of the three silver (I) halides AgCl, AgBr, and AgI has been investigated to pressures $p\ensuremath{\sim}13--16\mathrm{GPa}$ using angle-dispersive x-ray diffraction with an image-plate device. Principal attention paid characterization phase transitions in pressure range $p\ensuremath{\sim}7--13\mathrm{GPa}$ observed previously by optical resistivity techniques. In ambient-pressure rocksalt-structured transforms at $p=6.6(6)\mathrm{GPa}$ a monoclinic structure...
We adopt a reverse Monte Carlo refinement approach, using experimental X-ray total scattering data, to develop structure model for synthetic, hydrated amorphous calcium carbonate (ACC). The ACC is revealed consist of porous calcium-rich framework that supports interconnected channels containing water and molecules. existence previously unrecognized nanometer-scale channel network suggests mechanisms how additives can be accommodated within the provide temporary stabilization, as well...
The local structure of the low-temperature ordered phase negative thermal expansion (NTE) material has been investigated by reverse Monte Carlo (RMC) modeling neutron total scattering data. We obtain, for first time, quantitative measurements extent to which and polyhedra move as rigid units, we show that these values are consistent with predictions unit mode theory. suggest modes associated NTE. Our results do not support a recent interpretation x-ray-absorption fine spectroscopy data in...
Abstract AB O 3 perovskite‐type solid solutions display a large variety of structural and physical properties, which can be tuned by chemical composition or external parameters such as temperature, pressure, strain, electric, magnetic fields. Some show remarkably enhanced properties including colossal magnetoresistance giant piezoelectricity. It has been recognized that distortions, competing on the local level, are key to understanding tuning these remarkable yet, it remains challenge...
Each the same: A stable, recoverable, amorphous phase (see topology model) was produced by heating each of four different zeolitic imidazolate frameworks ZIF-1, -3, -4, and Co-ZIF-4. By comparing nanoindentation results, density measurements, X-ray total scattering it is concluded that structure equivalent in case. Amorphization only observed ZIFs encompassing unsubstituted ligands.