cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1510568
title: Framework flexibility and host-guest hydrogen bonding across the phases of a metal-organic perovskite CH3CH2NH3[Mg(HCO2)3]

description: Metal-organic perovskites offer many of the advantages of their ceramic analogues, with a range of exploitable functionality including ferroelectricity. Understanding the structural origins of these properties, however, requires a more detailed description of disorder than is currently available for many materials. Ethylammonium magnesium formate is an ideal candidate to study such behaviour, with two phase transitions involving substantial motion of both the Mg-formate framework and ethylammonium guests, and a polar, potentially ferroelectric structure at room temperature. We propose a total scattering study of the disordered ethylammonium ion as a function of temperature, in order to understand the properties of this material including substantial hysteresis in its phase transitions, and to direct the future engineering of ferroelectric framework materials.
DOI: 10.5286/isis.e.rb1520237
title: Using neutron crystallography for investigating protonation states of a catalytic arginine residue from chlorite dismutase

description: Chlorite dismutases (Clds) are metalloproteins containing heme b (i.e. Fe(III) in a porphyrin system) as redox cofactor. Clds are able to degrade toxic chlorite to chloride and dioxygen. This reaction is interesting from a biotechnological point of view as chlorite is a serious environmental pollutant and its bioremediation is an issue. However, mechanism of catalysis is not fully understood yet. Chlorite degradation activity is efficient at acidic pH, exhibiting its optimum at pH 5.0, but decreases significantly with rising pH. It is hypothesized that this depends, at least to a certain extent, on the protonation state of a conserved arginine residue. Investigating the protonation state of this residue under certain pH conditions by using neutron crystallography will highly contribute to understand Clds' reaction mechanism in general and the role of the conserved arginine in particular.
DOI: 10.5286/isis.e.rb1610162
title: Understanding Deep Earth Mineralogy: A High P/T study of CaSiO3 Perovskite

description: CaSiO3 perovskite is the third most abundant mineral in the Earth's lower mantle; it also occurs as a major phase at lower pressures and temperatures in subduction zones, where, for example, it may form ~25 wt% of subducted mid-ocean ridge basalt. Its crystal structure, ferroelastic phase transitions, elastic properties and equation of state are, therefore, of great significance for the interpretation of seismological data. The phase diagram of CaSiO3 perovskite is currently in a state of utter confusion, with computer simulations and experimental studies disagreeing widely as to the structures of CaSiO3 and the P/T conditions under which they occur. Recent work at the ESRF has shown that the introduction of 0.51.0 wt% of H2O stabilises a non-cubic phase to lower P & T. We propose to use PEARL to make an accurate structure determination H2O-doped CaSiO3 perovskite at 1250 K and 10 GPa.
DOI: 10.5286/isis.e.rb1610176
title: Magnetic structure below the metal-insulator transition of Pb2CaOsO6

description: This proposal is part of a project in which we explore the unusual physics of 5d transition metal oxides. Using a special high pressure technique, we have synthesised first samples of lead calcium osmate (Pb2CaOsO6). We found that Pb2CaOsO6 undergoes a metal-insulator transition at 80K, which for this material cannot be understood in the usual Mott-Hubbard scenario. It is more likely a rare realisation of a Slater transition, where the electronic ground state is renormalised by magnetic ordering.We have previously performed a Pb2CaOsO6 powder diffraction experiment on WISH. We were able to determine the propagation vector of the antiferromagnetic order, but the dataset did not allow a complete determination of the magnetic structure. To conclude our study, we here propose a magnetic neutron diffraction experiment of our newly synthesised Pb2CaOsO6 single crystal on WISH.
DOI: 10.5286/isis.e.rb1610402
title: Melting the long-range magnetic order in SrEr2O4 with an applied magnetic field

description: We have observed an interesting phenomenon of the destruction of long-range magnetic order in SrEr2O4 by a relatively modest applied magnetic field. For a field applied along the [001] direction (parallel to the magnetic moments on one of the Er3+ sites) a field of 0.2 - 0.4 tesla is sufficient to replace well-defined sharp Bragg peaks with the diffuse scattering features corresponding to a much shorter magnetic correlation length. At higher fields the long-range order is restored, but it is different from the zero-field state. The aim of this proposal is to investigate the unusual field-induced transition and clarify the nature of the high-field magnetic order.
DOI: 10.5286/isis.e.rb1610434
title: Searching for the missing phase of SrTiO3; commissioning a new cryogenic pressure cell for WISH.

description: Generating pressure above 1GPa for neutron diffraction typically requires the use of a Paris-Edinburgh press. Whilst the presses operate very reliably at ambient temperature, their design is not well suited for low temperature studies below 60 Kelvin. We have developed, in collaboration with the ISIS facility, a new compact pressure cell for use at temperatures less than 1 Kelvin, operable over a similar pressure range. The cell can be cooled quickly using conventional CCRs and cryostats, and has been designed to avoid the need to warm the cell to room temperature to change the pressure. Here we hope to complete the commissioning of this pressure cell, incorporating several new design improvements. As a trial experiment, we have chosen to study SrTiO3; we hope to determine the existence of a new phase under pressure at base temperatures, which is otherwise suppressed by quantum effects.
DOI: 10.5286/isis.e.rb1610444
title: Mapping the highly complex magnetic phase diagram of TmCu

description: This proposal forms part of our project to investigate the implications of non-trivial real-space topology in multi-k magnetic structures. We are here focusing on the rare earth intermetallic TmCu. On the seemingly uncomplicated premise of a simple cubic lattice of large Tm3+ magnetic moments develop magnetic phase diagrams of rarely seen complexity. Our interest in the clarification of these magnetic states is fuelled mainly by our initial observation of large unconventional Hall signals associated with distinct phase pockets. We have recently performed a first part of this single crystal neutron diffraction study using reserve day beam time. This experiment has been highly successful and the WISH high field setup has proven to be uniquely suited to our needs. We here propose to complete this study by investigating our sample in the remaining two high-symmetry field orientations.
DOI: 10.5286/isis.e.rb1610455
title: The structure of methane water fluid mixtures at high pressure

description: We have recently discovered that above 2 GPa in the liquid/fluid forms water and methane become miscible in proportions up to 33 mole% of methane.  This proposal is for time to study the structure of this remarkable liquid/fluid.
DOI: 10.5286/isis.e.rb1610506
title: Investigation of the magnetic frustration in ACr3As3 (A = K, Rb and Cs)

description: The recently discovered quasi-one-dimensional (Q1D) superconductor A2Cr3As3 (A=K, Rb and Cs with TC ≈ 6.1 K, 4.8 K and 2.2 K, respectively) has intrigued intensive studies. The unconventional superconducting nature has been revealed by both experimental and theoretical investigations. The related new compounds ACr3As3 (A = K, Rb and Cs) also have 1D (Cr3As3)∞ linear chains, and the interchain distance can be tuned by the incorporation of the alkali-metal cations with different sizes. The susceptibility measurements indicate a local-moment behaviour (T&gt;60K), and the moments freeze into a cluster spin-glass state below 5~6 K.  No superconductivity was observed in ACr3As3 materials, with increasing the interchain distance, the Cr effective moments increase monotonically. We propose to use inelastic neutron scattering to study the spin excitations in these compounds.
DOI: 10.5286/isis.e.rb1610518
title: Determining structure of D2S deuterium sulphide at high pressures up to 20 GPa

description: As it was reported recently in Nature Hydrogen sulphide conducts electricity with zero resistance at a record high temperature of 203 K. Authors of this high profile discovery find that when they subject samples of hydrogen sulphide to extremely high pressures 150 GPs in diamond anvil cells and cool them below 203 K, the samples display the classic hallmarks of superconductivity: zero electrical resistance and Meissner effect. Results of these experiments suggest that hydrogen sulphide seems to be a 'conventional' type one superconductor. Authors also argue that the phase responsible for high-Tc superconductivity in this system is likely to be H3S, formed from H2S by decomposition under pressure. Today the structure of H2S at high pressure and cryogenic temperatures is little-known. We propose diffraction measurements of D2S at high pressure up to 20 GPa and temperature range 120  300 K
DOI: 10.5286/isis.e.rb1720074
title: HIFI STUDY OF THE HETEROMETALLIC POLYMERS {[{(PTA)2CpRu-μ-CN-RuCp(PTA)2}-μ-CdCl3-]}n, {[{(PTA)2CpRu-μ-CN-RuCp(PTA)2}-μ-LaCl3-]}n and {[{(PTA

description: Our ability to control the synthesis of this kind of material has led to the development of a family of Ru-Ru-M-backbone organometallic compounds with general formula {[(PTA)2CpRu-μ-X-RuCp(PTA)2-μ-MCl3}n (X = CN-, SCN-; M = Au [2], Ni[3], Cd[4], Co[5]...). Our previous Xpress work with the polymers with X=CN-, SCN- and M = Cd, La, clearly demonstrates the muon has the potential to differentiate differences between structurally different ORGANOMETALLIC POLYMERS on the microscopic level. However, it raises several questions; in particular the exact nature of muonium addition in these materials and the influence of the SCN or CN linkage, as well as the magnetic inclusion, on the coupling behaviour. To answer these questions we therefore ask for time on the HiFi spectrometer to complete this study.
DOI: 10.5286/isis.e.rb1720090
title: Highly selective adsorptive SMOFs

description: In the area of metal-organic porous materials, supramolecular metal-organic frameworks (SMOFs) constitute a blooming alternative. Their examples are still relatively scarce when compared to MOFs (metal-organic frameworks), and as far as we are aware there is not any study dealing with the crystallographic location of adsorbate molecules within the porous structure. The materials selected for the current study are featured by being especially selective towards CO2 molecules. Thus, the current work aims to get deeper insight into the adsorptive behaviour of these materials since evidences on the mechanistic and pore occupation under different pressure and temperature conditions would enlighten the adsorption mechanistic of these materials and explain this remarkable adsorption selectivity.
DOI: 10.5286/isis.e.rb1720143
title: Investigating the dynamics of substituted aromatic liquids

description: This proposal aims to investigate the dynamics of ortho-/meta-/para- xylene, mesitylene and 1,3,5- Trihydroxybenzene. Improved understanding of their dynamics is relevant to these industrial processes. Previous beamtime using QENS (1610076, 1620133 and 1710298) have investigated the dynamics of benzene, toluene and ethylbenzene, respectively. This proposal would complete the range of aromatics and provide for a full comparison of the effect of the addition of methyl groups to benzene. A full knowledge of the diffusion properties of the liquids would greatly enhance our understanding of the dynamics of these aromatic molecules in both the pure liquid as well as provide the basis for examining their behavior in porous materials, for example heterogeneous catalysts.
DOI: 10.5286/isis.e.rb1720186
title: Mercury Sulphide Dimorphism in Thiogermanate Glasses

description: Crystalline mercury sulphide exists in two drastically different polymorphic forms: red chain-like insulator, alpha-HgS, and black tetrahedral narrow-band semiconductor, beta-HgS.  Using pulsed neutron and high-energy X-ray diffraction, we have shown recently that these two mercury bonding pattern are present simultaneously in mercury thioarsenate glasses HgS-As2S3 and govern their electronic, thermal and transport properties.  Vitreous arsenic sulphide is a 2D glass formed by AsS3/2 pyramids and the maximum fraction of tetrahedral mercury HgS4/4 is about 30 % for the HgS-As2S3 glass system.  The question arises whether this fraction will be higher or even predominant for tetrahedral glassy host GeS2.  The neutron diffraction studies of (HgS)x(GeS2)1-x glasses, 0 &lt; x &lt; 0.6, will give a definitive answer useful for practical applications of these new promising disordered systems.
DOI: 10.5286/isis.e.rb1720446
title: Extreme Muon Quantum Effects in Solid Acetone

description: Extreme muon quantum effects will be studied in the simple organic molecule acetone in deuterated and undeuterated forms using ALC spectroscopy to determine the quantum averaged hyperfine parameters of the state formed by muon addition to a C=O bond. These measurements will span between the low temperature solid phase which is dominated by quantum motion of the muon and the high temperature liquid phase where thermally activated vibrations of the muon within the molecule produce a significant temperature dependent contribution to the isotropic hyperfine constant. The results will be used to develop and test new computational methods for determining muon parameters that take these quantum and thermal averaging effects fully into account.
DOI: 10.5286/isis.e.rb1768029
title: Neutron diffraction studies on multiferroic NixMn1-xCr2O4 and Ni0.75Cu0.25Cr2O4.

description: Multiferroic materials (MF), in which ferromagnetism and ferroelectricity coexist, have attracted much attention in recent years. If the coupling between the magnetic and ferroelectric order is strong enough, MFs potentially allow the manipulation of electric and magnetic moments by magnetic and electric fields, respectively. Recently, we have synthesized multiferroic Ni1-xA1-xCr2O4 (A=Mn,Cu) to study the detail magnetic structure as a function of temperature (T) at low T by NPD. Initial measurements of T dependent XRD, dielectric & magnetization measurement have already done. In order to understand the origin of magnetoelectric MF behavior, it is necessary to understand the relation between its structural parameters and complex magnetic ordering. The structural studies as a function of T will provide microscopic level information of the origin of magnetoelectric coupling in these MFs.
DOI: 10.5286/isis.e.rb1800004
title: Feasibility study to search for a structural signal from nanobubbles in solution.

description: There has been much interest recently in the possible applications of nanobubbles in solution, due to their wide applications in many fields of science and technology, such as water treatment, biomedical engineering, and nanomaterials. Inspired by a recent publication (C Zhou, et al., "Formation of Stable Nanobubbles on Reconstructuing Lyophilized Formulations Containing Trehalose, J. Pharm. Sci., 105 (2016) 2249-2253) in which stable air bubbles were observed upon reconstitution of freeze-dried sugar samples, we would like to perform a feasibility study of studying these solutions on NIMROD. To this end some samples of freeze-dried sucrose have been obtained from Allergan in California. Water (H2O, D2O and mixture of these) will be added to these samples and agitated until the sugar is dissolved. Each sample will then be measured on NIMROD for approximately 1 hour each.
DOI: 10.5286/isis.e.rb1810714
title: Residual stress depth profiling in the vicinity of indentation in high-strength steel

description: The proposed experiment aims to map the residual stresses in the interior of 5 - 14 mm thick steel plates of two types of high-strength martensite steel using neutron diffraction. Two sets of samples will be tested: type 1 is 5 mm thick high-strength steel plate with lab-produced indentation, and type 2 is 13-14 mm thick steel samples cut-outs from a industrially used dump truck hopper. The experiment are expected to lead to previously unavailable data and insight into how the residual stress states in these types of high-strength steel compare to each other as well as change due to the real use. The proposed experiment is one part of a project involving several industrial and academic partners, who's aim is to study properties of new high strength steel, mainly related to hydrogen absorption and stress profiles due to real life usage.
DOI: 10.5286/isis.e.rb1820088
title: Lipopolysaccharide Functions as Bacterial Receptors to Antimicrobial Peptides

description: Neutron reflection (NR) is well established for studying molecular films such as lipid monolayers. Its high depth resolution combined with deuterium labelling can determine the amount and location of binding of antimicrobial peptides (AMPs). By unravelling how AMPs interact with model lipopolysaccharide (LPS) membranes NR can help us to develop strain-specific AMPs to target at Gram-negative bacteria whilst tuning their biocompatibility to mammalian cell hosts. we request 3 days on INTER or 4 days of Surf to complete this work. Inter is preferred due to weak but measurable signals from h-lipid-h-peptide in NRW.
DOI: 10.5286/isis.e.rb1820121
title: Structural Investigations of Mixed-anion Argyrodites

description: Argyrodites exhibit promising thermoelectric (TE) properties but a structural transition causes cracking of ingots on cooling to ambient temperature, introducing problems for device construction. We have prepared series of mixed-anion derivatives of Cu8GeS6, containing halide ions that show marked reductions in the phase-transition temperature and the stabilization of the high-temperature structure at room temperature, eliminating problems of cracking. Neutron diffraction will be used to investigate the role of the larger halide ions (Br and I) in suppressing the structural transition and to provide the first structural characterization of the low temperature form of mixed-anion phases. The data will also provide information on the mobility of copper ions and shed light on the origin of the low thermal conductivity that results in promising TE performance even in non-optimized materials.
DOI: 10.5286/isis.e.rb1820172
title: Compressibility and Tilting of Polyhedra within Sr2NiMoO6 at High Pressure

description: Ordered double perovskites (also known as elpasolites) have the general formula A2BBO6 where A is generally a rare earth metal or alkaline earth metal and where B and B are typically transition metal or main group metal cations. There is a wide variety of structural and compositional diversity of such perovskites. As such this class of materials exhibits a wide range of physical properties which are controlled by doping, temperature and pressure. The aristotype double perovskite would be cubic, however the majority of double perovskites crystallise in a lower symmetry as a result of co-operative octahedral tilting. Changes in temperature and pressure are known to cause phase transitions in the ordered perovskites in that the thermodynamic variable is able to change the sample volume and the octahedral tilts are able to react to these volume changes.
DOI: 10.5286/isis.e.rb1820219
title: Disrupting structural correlations in the Na-Ca-NH3 system

description: Na or Ca, when dissolved in ammonia, yield metallic liquids. These liquids are fully miscible and yet each possesses a different intermediate-range order depending on the parent metal. Ca is a 'structure forming' core in Ca-NH3, possessing a sharply defined pre-peak in its structure factor.  Na, on the other hand, is not and possesses no pre-peak until the highest possible concentrations of metal. This is surprising considering the similar cationic radii of Na+ and Ca2+, and the picture of the metal-ammonia solutions as core-like cations with a vast majority of the conduction electron density residing several angstroms from these cores. This study aims to determine the effect of being a tertiary system on intermediate-range structural correlations in Na-Ca-NH3, as dependant on the metal concentration and the concentration of conduction electrons.
DOI: 10.5286/isis.e.rb1820328
title: 2D vs. 3D ordering in CrCl3, a Heisenberg antiferromagnet on a honeycomb lattice

description: Van der Waals solids containing two-dimensional lattices of magnetic moments with only weak interlayer coupling have attracted significant scientific interest due to their applications in creating designer heterostructures. In particular, the Cr trihalides (CrX3 with X=F, Cl, Br, I) belong to this class of material and their ferromagnetic semiconducting properties make them especially attractive in the development of low-dimensional spintronic devices. Recent studies of CrCl3 have called into question aspects of our current understanding of its magnetic properties and proposed the existence of a temperature regime with 2D intralayer magnetic order but no 3D interlayer order. We would like to investigate this intriguing proposition and probe the magnetic behaviour of CrCl3, using our knowledge from our ongoing study of the very similar alpha-RuCl3.
DOI: 10.5286/isis.e.rb1820329
title: Magnetic excitations in magnetoelectric pyroxenes CaMGe2O6 (M=Mn, Co)

description: Magnetoelectric materials have been the subject of a considerable amount of research activity for their fundamental scientific interest and potential applications in technology, such as magnetoelectric random access memory. We have recently reported the magnetoelectric and magnetic properties of a clinopyroxene compound CaMnGe2O6. The aim of this proposed experiment is to determine the strengths of the various exchange integrals in magnetoelectric CaMnGe2O6 through inelastic neutron scattering and to, in turn, gain insight into the origin and role of frustration in this family.
DOI: 10.5286/isis.e.rb1820430
title: Introducing the O-antigen in Bacterial Outer Membrane in vitro Models Pt. III The effect upon antibiotic sensitivity

description: The Gram negative bacterial outer membrane protects the bacterium from external toxins such as antibiotics. This is partially responsible for Gram negative bacteria becoming the fastest emerging source of antibiotic resistance. We are developing models of these bacterial outer membranes and have successfully recreated the characteristic  lipid asymmetry (with lipopolysaccharide (LPS) on the outer leaflet and phospholipids on the inner). In order to fully recreate the membranes we will need to incorporate more complex LPS versions to mimic pathogenic bacteria. Pathogenic bacteria contain a proportion of longer LPS molecules which are related to their virulence. Recently we have  incorporated LPS containing one or two O antigens into the model and now wish to understand the role of the O antigen in resistance towards outer membrane disrupting antibiotics such as polymyxin B.
DOI: 10.5286/isis.e.rb1820487
title: Solvation of sodium by glyme-based electrolytes for sodium intercalation into graphite

description: Here we propose to study the local structure of sodium ion in glyme electrolytes for sodium ion batteries. Glyme electrolyte are linear ethers of the structure CH3-O-[CH2-CH2-O]n-CH3 of which we plan to study three solution with n=1, 2 and 3 respectively. These electrolyte have already prove to have several desirable features for sodium ion batteries enabling graphite to be used as a anode and strongly inhibits the solid electrolyte interface formation. It has also been shown that the capacity of the sodium ion battery depends on the length of the glyme molecule. By understanding the local structure around the sodium ion we hope to understand how this effect the capacity of the battery and how this allows for sodium intercalation into graphite when other electrolyte does not allow for this reaction to occur.