10,059 Works

Structural distortions and partial order in the selenate and chromate analogues of mirabilite

The mineral mirabilite (di-sodium sulfate decahydrate) has been extensively studied by X-ray and neutron powder and single-crystal diffraction methods. The structure contains an interesting square ring of water molecules that is fully disordered at high temperatures, but which becomes partially ordered on cooling. One of the factors that appears to control this ordering process is a thermally-induced libration of the sulfate ions to which the square rings are hydrogen-bonded. In an effort to understand this...

Structural distortions and partial order in the selenate and chromate analogues of mirabilite

The mineral mirabilite (di-sodium sulfate decahydrate) has been extensively studied by X-ray and neutron powder and single-crystal diffraction methods. The structure contains an interesting square ring of water molecules that is fully disordered at high temperatures, but which becomes partially ordered on cooling. One of the factors that appears to control this ordering process is a thermally-induced libration of the sulfate ions to which the square rings are hydrogen-bonded. In an effort to understand this...

Magnetic excitations in AgCrSe2

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AgCrSe2 has emerged as a material of great interest due it its good thermoelectric performance. It also has an interesting cycloidal magnetic structure. While studying the thermoelectric parameters we have discovered that the previously published magnetic interactions are inconsistent with the magnetic structure. We now propose to study the magnetic excitations to higher energy than have previously been possible using MAPS which will allow us to resolve this.

Diffuse scattering investigation of out-of-equilibrium states in spin ice

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The spin ice material Dy2Ti2O7 is a frustrated material where the magnetic spins on a tetrahedra can only point into or out of the 111 crystallographic axis. Moreover, long range dipolar interactions competing with the local exchange means that 2 spins point into and 2 out of the 111 axis, and this state is degenerate, meaning there is a manifold of lowest energy states. Excitations out of this ground state make a 3 in, 1...

Determining the Crystal and Magnetic Structures of [Li(oxalate)]2[Co5(OH)8]

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Dense corrdination frameworks that contain inorganic centres connected into extended lattices by polyatomic anions often adopt highly anisotropic structures. Thus they often have strong magnetic interactions in only one or two dimensions and, in the latter case, can also be designed so they have strongly competing interaction that give rise to magnetic frustration. Recently discovered [Li(oxalate)]2[Co5(OH)8] appears likely to be one such two dimensional magnet. We will determine the structure of its antiferromagnetic state, which...

Hydration behaviour of uranyl chloride: from fundamental chemistry to environmental applications

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In water uranium exists almost exclusively as the uranyl ion [UO2]2+. In the presence of halides these can form complexes of the type [UO2(H2O)nClx]2-x, whose thermodynamics and structures in solution are not fully understood. This is important as high halide concentrations are expected to be found in spent nuclear fuels or under certain environmental conditions. In this work we propose to study the reaction of uranyl chloride [UO2(H2O)5][Cl]2 with LiCl under increasing halide concentrations to...

Investigating the composition of small Hellenistic silver coins using negative muons

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The quality of ancient silver coinage is often seen as a comment on the fiscal health of the issuing states. This is nowhere more apparent than with Roman coinages, which witnessed heavy debasements during the first three centuries of our era. Two processes are detectable: a reduction in the fineness of the alloys; and a reduction in weight standards. However, the hypothesis here is that the two processes are interlinked, and that the second is...

How do Surfactants Interact with Complex Monoclonal Antibodies at Oil/Water Interfaces?

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Heavily bio-engineered monoclonal antibodies (mAbs) are an increasingly important trend in the biopharmaceutical industry. However, these mAbs are often destabilised by the silicone oil found in pre-filled syringes, which are the preferred storage and application method for these drugs. This effect can be reduced by adding biologically safe surfactants to the formulation, but the mechanism by which this protects the mAb is currently not proven. This study will investigate the mAb-surfactant-silicone oil interaction, using several...

Title: IMAT commissioning : use of cold neutrons to discriminate minerals with similar density

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One of the major challenges of XCT is the lack of X-ray penetration in the dense mineral samples and the distinction of minerals with close atomic number Z. The lack of penetration results in beam hardening especially for minerals with densities higher than 3g/cm3. The utilisation of cold neutrons at IMAT with optimal neutron wavelengths (neutron energy dependant experiment) can be used to discriminate different iron ore oxides (hematite and magnetite) as well as 11...

Discriminating the conformation of G4 DNA by SANS.

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Guanine-­rich DNA sequences are prone to fold into stable helical four­-stranded structures called G­quadruplexes (G4). These systems have drawn the attention of a number of scientists in both basic and applied research fields, including structural biophysics, cancer biology, novel therapeutics through to nanotechnology. And most importantly, G4s have been proposed as selective and effective therapeutic anticancer targets. However, the intrinsic polymorphism of G4s makes very challenging the prediction of the architectural folds encoded in guanine-rich...

High Energy Spin Excitation in Cu3Zn(OD)6FBr

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Z2 quantum spin liquid is relatively easier to be identified since one may be satisfied as far as no symmetry breaking and gapped spin excitation continuum are observed. The kagome Heisenberg antiferromagnet ZnCu3(OH)6Cl2 is the most promising candidate for the studying of QSLs with large magnetic interactions and clear sign of continuum excitation. But very limited excitation data has been collected at high energy. We have successfully synthesized Cu3Zn(OH)6FBr with AA kagome stacking. It has...

Crystal structure of Bi2W2O9

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Exploration for Spin Liquid State in Spinel Titanates

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We explore for the spin liquid state. Recently, the theoretical studies suggest that not only the frustrated lattice but also a structural fluctuation and disorder are important for the spin liquid state. The spinel titanate MgTi2O4 undergoes the structural transition from the cubic to tetragonal phase. The Ti ions are dimerized and form the spin singlet pairs. In the Mg-substituted Mg1+xTi2-xO4, though the tetragonal phase collapses, the Ti structural fluctuation remains and can induce the...

Dataset supporting the publication: \"Structure and vibrational spectroscopy of lithium and potassium methanesulfonates\" by Parker, Revill-Hivet, Nye and Gutmann, published in Royal Society Open Science 2020

Stewart Parker, Emilie Revill-Hivet, Daniel Nye & Matthias Gutmann
The dataset comprises the experimental and computational studies that form the basis of the publication: "Structure and vibrational spectroscopy of lithium and potassium methanesulfonates" by Parker, Revill-Hivet, Nye and Gutmann, published in Royal Society Open Science (2020). The dataset consists of three zip files: "A-Crystallographic_information.zip", "B-Experimental_spectra.zip", "C-CASTEP.zip", . "A-Crystallographic_information.zip" contains cif files of the structures. These can be read by any text reader or loaded into any suitable program e.g. Jmol (available from: http://jmol.sourceforge.net/ )...

SEC-SANS for structure determination for membrane proteins in polymer-stabilised nanodiscs

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This proposal is a continuation from our upcoming experiment aimed at using Size-Exclusion Chromatography coupled with SANS (SEC-SANS) to ensure accurate measurement of membrane proteins supported in Poly(Styrene-Maleic Acid) (SMA) lipid-nanodiscs. These polymer-formed nanodiscs are an appealing choice compared to more traditional alternatives for protein extraction and structural studies, as preparations are stable, quick, low cost and can be produced in large quantities. In this proposal we propose to use again the membrane proteins gramicidin...

From polymer molecular architecture to lubrication efficacy and CO2 emission reduction

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In collaboration with Infineum (a world-leading engine-oil additive company), we propose a SANS study of self-assembly of novel polymethacrylate (PMA) block copolymers as a function of concentration and temperature. Preliminary SANS results for a diblock polymer architecture have revealed a core-shell micelle structure in a model oil (deuterated n-dodecane). Here different polymer architectures will be investigated (multiblock, diblock, random, and homo). The results will complement our ongoing interfacial structure and friction/lubrication studies using XRR and...

Tracking CO2-mineralisation to magnesite and eco-cements

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Magnesite is essential to fertilizer, paper, glass, construction; most recently as eco-cement, at Mt-Gt scales. Mg2+ sources are plentiful recoverable via mineral carbonation of Mg-silicate, whose deposits are @ 10^5 Gt with magnesite being the most stable Mg-carbonate under all conditions. Yet, MgCO3-mineralisation is retarded by Mg-dehydration. Industrially magnesite is produced with high-T/P condition, unlike ambient formation in nature, accelerated by impurities in ground water (HS-, SiO4-2, RCOO-), as-yet irreproducible in the lab. Geochemical evidence...

Comparison of the Compression Behaviour of BaSnO3 and Ba0.575Sr0.425SnO3

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We propose to study the effect of pressure on the structure of the tetragonal Ba0.575Sr0.425SnO3, The behaviour will be compared to the compression of the cubic BaSnO3 (parent compound). At room temperature the perovskite system Ba1-xSrxSnO3 shows a series of phases in the sequence orthorhombic (Pbnm), orthorhombic (Ibmm), tetragonal (I4/mcm), and cubic (Pm-3m) [4]. These are a consequence of the sequential introduction of cooperative tilting of the corner sharing SnO6 octahedra resulting from the changes...

Dynamical characterization of a new multicomponent membrane (gCN/PTI mixed with Nafion) for energy applications.

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Proton exchange membranes are essential components of devices where is required to transport H+ while blocking the flow of other ions and molecules used as reactants. The most common ionomeric material is Nafion, which has excellent H+ conductivity, despite having poor selectivity against other ions and small molecules. It is been found that introducing ~1% gCN (graphitic carbon nitrides) into Nafion/SPEEK membranes enhances H+ conduction. We propose to use neutron scattering to investigate the effects...

Accounting for textural effects on total scattering data and the pair-distribution function

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The total scattering technique has become an invaluable method for probing the local structure of materials in a host of interesting fields. However, the technique is reliant on some assumptions about the nature of the material being studied that currently limits the application of the technique in certain fields. Of particularly significance is the orientation of grains within the sample, known as texture, which can be strongly dependent on the method of manufacture of the...

Measurement of vibrational spectra in high-thermal-conductivity ceramics

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In high-voltage electronics, heat dissipation is a major challenge. Ideally the materials in these devices will have a high thermal conductivity; a property determined by vibrations in the material. In order to improve understanding of these materials and develop better alternatives, it is helpful to have a good theoretical model of these vibrations: available approaches include force-fields, tight-binding and density-functional theory. These simulations may be compared to and calibrated against spectra from Raman measurements and...

ISIS Commercial access : TRAD

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ISIS commercial access.

Investigation of magnetic structure of new multiferroic compound LiFeV2O7

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Ferroelectric polarization in type-II multiferroics is induced below long-range magnetic ordering with certain magnetic structure that breaks the inversion symmetry. Here we have investigated polar magnetic oxide LiFeV2O7 which shows a change in polarization at the magnetic ordering. This indicates that the magnetic structure couples to lattice and induces a change in electric polarization. Therefore, it is important to understand the nature of the magnetic structure which is responsible for inducing polarization. It is for...

Earth Abundant NASICON Materials for Lithium Battery Applications, Li3Fe(MoO4)3 and Li1.6Mn2.2(MoO4)3

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The framework materials Li3Fe(MoO4)3 and Li1.6Mn2.2(MoO4)3 contain networks of Fe/MnO6 and MoO4 units. These compounds are similar structures to the recently reported cathode material Li3Cr(MoO4)3 showing exceptional lithium storage based on redox activity of Mo in addition to the transition metal. We have found exceptionally high Li+ conductivity in the title phases. The structures of these materials have been determined previously using X-ray scattering, which is notoriously unreliable in detecting the subtle interstitial sites and...

Structural study of the effect of barium doping in Sr3Ru2O7

The capability of systematically tuning electronic properties of strongly correlated electron systems is key to unraveling the mechanisms underlying the observed physics. Sr3Ru2O7 has been widely studied due to a highly correlated zero field ground state dominated by magnetic interactions giving rise to a quantum phase transition and formation of an unconventional high-field phase. Its structure consists of bilayers of RuO6 octahedra separated by SrO layers offering an ideal test case for the control of...

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