cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1720443
title: Towards reliable residual stress characterization in dissimilar metal welds

description: The proposed experiment is a continuation of the initial studies carried out on SALSA instrument (ILL, Grenoble) as part of the collaborative PhD project jointly funded by the Open University (UK) and ILL. The first proposal formed the foundations for investigating methods of improving the characterization of residual stress in dissimilar metal welds. This proposed experiment is intended to continue the process of developing a methodology for quantifying and correcting for the errors specific to determining residual stress in dissimilar metal welds, specifically the issue of pseudo strains when the gauge volume traverses an internal boundary. The findings will support the planned inclusion of a best practice guide for neutron diffraction measurements on DMWs in the UK nuclear industry, R6 structural integrity code.
DOI: 10.5286/isis.e.rb1720477
title: Understanding of Competing Magnetic Processes in La0.7Sr0.3MnxFe1-xO3 Perovskite

description: The aim of this experiment is to complete the understanding of the complex nature of the structural and magnetic interactions in the  La0.7Sr0.3Mn1-xFexO3 series of materials in particular x=0, 0.2, 0.5 and 0.7. Perovskite manganates with the general formula L1-xAxMnO3 (e.g. L=La, Pr , Nd and A=Ca and Sr) have attracted significant interest as a result of their unusual transport and magnetic properties, in particular colossal magnetoresistance (CMR) behaviour. The physical properties of the materials are controlled by various factors including concentration of the divalent A ion and relative atomic radii of the ions which control the structural distortions away from the cubic aristotype and therefore impact strongly on the electronic and magnetic structures.
DOI: 10.5286/isis.e.rb1510074
title: Investigation for pressure-induced ferroelectric polarization flop phenomenon in multiferroic TbMnO3 with hybrid-anvil high pressure cell

description: We propose to perform neutron diffraction experiments under high-pressure on multiferroic TbMnO3 using WISH in combination with hybrid-anvil-type high-pressure device. Recently, the pressure-induced electric polarization flop phenomenon was discovered in TbMnO3, which was observed in the electric polarization measurements under pressure above 4.5 GPa. (Aoyama et al, Nature Comm. 5 4927 (2014)) Although the magnetic ordering in high-pressure phase was predicted as E-type antiferromagnetic order due to a giant ferroelectric polarization induced by pressure (and neutron powder diffraction at low pressure below 3.6 GPa), direct observation of magnetic ordering above 4.5 GPa has not been reported so far. In this study, we investigate how the magnetic structure is changed by pressure up to 6 GPa, using the hybrid-anvil-type high-pressure cell.
DOI: 10.5286/isis.e.rb1510537
title: Host-Guest Interactions at the Surface of a Cucurbit[8]uril Threaded Polymer

description: The increased use of polymers in engineering applications previously dominated by metals or ceramics gives the opportunity for direct tailoring of the surface characteristics via modification of the polymer's chemistry. The incorporation of binding sites into a polymer allows for a wider range of surface interactions. We propose to study a host-guest interaction for a polyamide-imide containing cucurbit[8]urils; barrel-shaped molecules threaded onto the polymer via a viologen monomer. A second molecule can be accommodated within the cucurbit[8]uril and so will bind an anthracene containing polymer present in the solution. We would characterise the bare surface of the unmodified polyamide-imide, the viologen modified polymer and the cucurbit[8]uril threaded version, study the adsorption of our additive at various concentrations on these surfaces and characterise the full monolayer formed.
DOI: 10.5286/isis.e.rb1510559
title: Microstructure of Homoeopathic Organic Solar Cells

description: Much progress has been made researching organic solar cells (OSC) in the last two decades, but the field still holds surprises. Until recently, the general assumption was that for efficient operation a mixture of about equal parts of donor and acceptor molecules is required in the photovoltaic active layer of OSC. However, C. Tang, one of the pioneers of OSC, and his team published an OSC with only very little donor molecules (hence the name "homoeopathic solar cells") that should not work at all, or at least not as well as they do according to current understanding. It is not clear to what extend a new operating principle for OSC has been found and literature contains contradicting results. Key objective of this proposal is to use neutrons for the investigating of the so far unknown distribution of donor and acceptor molecules, which holds the key to better understand these solar cells.
DOI: 10.5286/isis.e.rb1510631
title: Ex-situ reflectometry studies of surface iron/ruthenium nitriding under ammonia decomposition conditions

description: Ammonia decomposition will be performed ex situ at different temperatures on silicon surfaces with 50 nm of either iron or ruthenium. The main objective of the neutron reflectometry analysis is to determine the concentrations of the different nitride phases, such that we are able to find out which nitride phase is the most active in decomposing ammonia. This will also provide information about the reverse reaction of ammonia formation on iron and ruthenium surfaces, which is of great industrial importance (ammonia is synthesised on the hundred-megatonne scale each year), as well as the industrial process of nitriding.
DOI: 10.5286/isis.e.rb1520036
title: Crystal structures of Na2MoO4.10H2O, Na2WO4.10H2O and Na2MnO4.10H2O.

description: Chemical substitution is a valuable technique for probing the behaviour of materials since this exerts a stress comparable in many respects to changes in pressure or temperature. We have used this method to study the properties of a common earth and planetary mineral known as mirabilite - sodium sulfate decahydrate. It has long been known that analogous decahydrates can also be prepared from sodium selenate, sodium chromate, sodium molybdate, sodium tungstate, sodium manganate and sodium monofluorophosphate. Until now, the crystal structures of the molybdate, tungstate and manganate were not known. However, we have recently been able to determine their heavy-atom arrangements from X-ray powder diffraction data. We propose to use neutron single-crystal diffraction to complete the structural characterisation (including H-atoms) with the highest accuracy using SXD.
DOI: 10.5286/isis.e.rb1610060
title: Adsorption of an Anionic Surfactant on Anionic Surfaces in the Presence of Caesium Ions

description: In this proposal we request beamtime on the Inter reflectometer to study the unexpected adsorption behaviour of the surfactant bis(2-ethylhexyl) sulfosuccinate caesium salt (Cs(AOT)) on both silica and mica surfaces as a function of temperature. This builds on previous ISIS work where the nature of the cation was found to have a big effect on the surprising adsorption of organic anions to an anionic surface. In particular, extending the work where we have observed a big difference in adsorption of the sodium and calcium AOT salts (on both mica and silicon substrates). In this work we directly challenge the divalent ion bridging mechanism for this anion on anion adsorption by adsorption with a monovalent cation.
DOI: 10.5286/isis.e.rb1610161
title: QENS Study of Proton Conducting Metal-Organic Framework Materials

description: The development of new functional metal-organic frameworks (MOFs) is receiving considerable attention worldwide owing to their potential for gas storage, ionic conductivity, and catalysis. We seek to develop new solid proton conductors based upon MOFs and request 5 days on IRIS to study the motion of active protons in two functional porous MOF materials [NOTT-500(Co,Ni)]. This proposed study will investigate the diffusion properties exhibited by these active protons from the MOF hosts. These two MOFs exhibit high proton conductivity (4.5 x 10-4 Scm-1 at 25 oC under 98%RH), and QENS study on the dry sample has suggested a spherical free diffusion mechanism for proton transfer within the framework lattice, representing the first example of such in MOFs. The proposed study aims to reveal the full nature of the proton conductivity by analysing the QENS data of wet sample under 98%RH.
DOI: 10.5286/isis.e.rb1610180
title: Gas Loading Effects on the Quantum Methyl Tunnelling Phenomenon in Zeolitic Imidazolate Framework-8 [Continuation of RB1510529 at OSIRIS]

description: This proposal is a continuation access to a recent experiment conducted at OSIRIS (RB1510529) to study the quantum tunneling characteristics of ZIF-8, which is a cubic metal-organic framework adopting a sodalite architecture. We will employ quasi-elastic neutron spectroscopy (QENS) to investigate in great detail the effects of varying gas dosing (pore filling effect) on the quantum rotation behaviour of the methyl groups present in ZIF-8. The results are essential to the completion of our recent study, specifically to enable detailed understanding of the mechanism(s) responsible for tunnelling response of Ar and N2 gas. This work may open up new science towards leveraging the emerging field of quantum molecular rotors in the context of metal-organic frameworks (MOFs).
DOI: 10.5286/isis.e.rb1610326
title: Shaping silica to mesoscale architectures at room-temperature

description: Hierarchical zeolites with molecular order at both the micropore (&lt;2nm) and mesopore (2-50nm) level are able to combine confinement effects in catalysis without suffering from diffusional limitations. Unfortunately, the key question standing central towards hierarchical zeolite synthesis - "should one meso-shape condensed silica before bulk crystallisation, or create this organisation with already crystalline structures?" has not at all been answered. We have in earlier work shown that several popular structures, such as stacked zeolite sheets and MCM-41 can obtain their meso-scale order already during the process of silica condensation at room temperature. The proposed work intends to build on these results, and reveal the dynamics of structure-directing agents in structure direction at the meso-level. The work will contribute to the development of industrially relevant materials.
DOI: 10.5286/isis.e.rb1610334
title: Adsorption of polyacrylamide at silica/water interfaces

description: This proposal presents a structural study of the adsorbed structure of partially hydrolysed polyacrylamide layers on silica/silicon surface from water. This follows from recent work where we could not see surface bridging of the polymer polyacrylic acid with added divalent ions. This has been attributed to the requirement for a stoichiometric amount of divalent cations and the complete absence of monovalent ions.  In this short work we aim to consider the stoichiometric case of cation and polymer ions. However, due to the very low solubility of the calcium salt of polyacrylic acid, we propose to use partially hydrolysed polyacrylamide.
DOI: 10.5286/isis.e.rb1620117
title: Thermodynamic Control of Isotopic Polymorphism

description: Co-crystals of 4-methylpyridine and pentachlorophenol (MP-PCP) exhibit the very unusual property of isotopic polymorphism, formation of different phases by samples differing only in isotopic composition. Isotopically normal MP and PCP co-crystals are triclinic, but when the phenolic oxygen is deuterated, the structure is monoclinic.  The triclinic deuterated and the isotopically normal monoclinic phases have not been described.  Statistical thermodynamic modelling based on DFT calculations indicates that the triclinic deuterated form should become competitive at low temperature, and this has been confirmed by crystal growth at 243 K which yields a mixed monoclinic and triclinic sample. The aim of this proposal is to follow crystal growth of this form by in situ by neutron powder diffraction, confirming the calculations and obtaining unambiguously phase pure sample of the triclinic deuter
DOI: 10.5286/isis.e.rb1620128
title: Dynamical process of helical-biskyrmion transformation of hexagonal magnet MnNiGa probed by SANS

description: Magnetic skyrmions are vortex-like, magnetic-spin objects that were lately discovered in bulk chiral magnetic materials. Recently, we discovered super stable magnetic biskyrmions (or skyrmion molecules) which is a new type of skyrmmion formed by two skyrmions of opposite spin helicities, in an extremely wide temperature range of 10 K to 350 K in MnNiGa sample by the combination of in-situ Lorentz transmission electron microscopy images and magnetoresistivity and topological Hall effect measurements (submitted to Adv. Mater.). However, the magnetic biskyrmions in this MnNiGa material have not been determined experimentally by neutron scattering and their physical origin also remains unclear. Aim to solve these problems, here we propose a SANS study of the magnetic biskyrmions lattice kinetics as a function of magnetic field at different temperatures.
DOI: 10.5286/isis.e.rb1700049
title: Study of Corannulene (C20H10) radicals

description: Carbon nanostructures presenting charge-transfer behavior (e.g. fullerene) can display high affinity to hydrogen and are promising materials for reversible hydrogen storage. Corannulene (C20H10) is a bowl shaped molecule which is 1/3 of C60 (fullerene) and, similar to it, can be intercalated by alkali metals, forming charge-tranfer salts.Muon spin spectroscopy (µSR) has proved to be essential in the investigation of hydrogenation mechanisms in intercalated fullerenes and we recently found a similar µSR behavior in C20H10. This proposal seeks to shed more light on the C-H radicals formation in C20H10 when this is hydrogenated and the results will be useful in further studies of alkali intercalated C20H10 compounds for hydrogen storage applications.
DOI: 10.5286/isis.e.rb1710008
title: HEAT-INDUCED CHANGES IN HUMAN BONE PROBED BY NEUTRON VIBRATIONAL SPECTROSCOPY

description: Neutron vibrational spectroscopy is applied to the study of burned human skeletal remains, as an innovative way of tackling heat-induced changes in human bone, which will have a significant impact in forensic, bioanthropological and archaeological contexts. The results, coupled to Raman and FTIR data, will lead to an improved understanding of the changes undergone by bone upon burning events, allowing a reliable assessment of the subsequent changes and ultimately relating burned to pre-burned parameters. A quantitative relationship between spectroscopic parameters, macroscopic dimensional variations in burned bones and specific burning conditions (e.g. temperature and duration) is sought. This work follows two experiments on MAPS (RB1520001 and 1620027), which constitute the first studies of human burned bones by neutron techniques. Our first results were recently published [1].
DOI: 10.5286/isis.e.rb1710117
title: Structure of water subjected to a static electric field

description: The behavior of liquid water under an electric field is a crucial phenomenon in science and engineering. However, its detailed description at a microscopic level is still far from being complete.We have recently looked at the effect induced by a relatively modest static electric field on the water proton environment with a Deep Inelastic Neutron Scattering experiment on VESUVIO. This kind of experiment can provide information on the energy landscape felt by water protons, and in particular on the shape and relative amplitudes of the potential wells representing the covalent and hydrogen bond. Results obtained at 300 K suggest a delocalization of the proton over the two sites of this double well potential when the electric field is switched on. We would like to find out if the observed effect of the electric field on water proton environment has a counterpart on water structure.
DOI: 10.5286/isis.e.rb1710227
title: Neutron Diffraction Study of Deformation in Coarse-Grained Cast Alpha-Uranium

description: This experiment aims to obtain experimental data to validate crystal plasticity modelling of a metal with a complex, anisotropic, crystal structure.  We propose to measure the evolution of lattice strain and texture with deformation of coarse-grained cast alpha-uranium under both tension and compression during loading and unloading.  The onset of crystal plasticity will be obtained via the deviation from linearity of the stress vs. lattice strain for the different families of grain orientations. Intergranular strains will be calculated and compared with existing data from finer-grained wrought material. We will also investigate the suitability of the technique to detect the formation of deformation twins in uranium by identifying lattice relaxation.
DOI: 10.5286/isis.e.rb1710244
title: muSR investigations of magnetodielectric system Co[C16H15CoN5O2] in metal-organic-framework

description: Our motivation is to design a multiferroic system in multmetal-organic-framework (MOF) . The flexibility in geometry and different types of  organic network in MOF system allow us to prepare such MOFs. However, to enhance the magnetic ordering and magnetoelectric coupling strength, we first need to understand the exact mechanism of multiferrocity and  cross-coupling. We have synthesized and studied a new MOF system  Co[C16H15CoN5O2], which is also a spin-chain system. A complex magnetic ordering below 15 K with magnetodielectric coupling and relaxor ferroelectric-type behavior around 100 K is established.  We plan to investigate the magnetic ground state and  nature of magnetic interaction through muSR study down to 1.5 K in zero-field and longitudinal field of 4.5 KOe, which will shade light on magnetodielectric coupling mechanism as well; hence, a route to design our expected MOF.
DOI: 10.5286/isis.e.rb1710283
title: Multilayer Heusler Alloy Thin Films for Spin Seebeck Devices

description: The spin Seebeck effect (SSE) is a relatively new phenomenon that could be harnessed for waste heat recovery. Its advantages lie with a new device architecture (compared to conventional thermoelectric generators) that would not only reduce the cost of fabrication but also enable separation of the key drivers of device efficiency: electric and thermal conductivity of certain active components. We are exploring Co_2MnSi as a potential material for SSE based devices having optimised the deposition conditions with previous PNR. Recent work has demonstrated an enhancement of the spin Seebeck effect on construction of multilayers such as {Fe_3O_4:Pt}. In this study we are investigating multilayer {Co_2MnSi:Pt} films prepared with and without an annealing step in order to reconcile differences in the observed spin Seebeck voltages.
DOI: 10.5286/isis.e.rb1720045
title: Dynamics of in Poly(vinyl alcohol)-SiC Nanofiber Composite

description: Inorganic-organic hybrid nanocomposites are formed by incorporating inorganic nanoparticles in soft organic polymer matrices. The dynamics of the polymer can be affected due to its interaction with the nanoparticles. It is important to investigate the dynamical behaviour of the naonocomposites and correlation with their mechanical properties. This depends on the natureand loading of the nanoparticle, the type of polymer matrix and the interaction between nanoparticle and polymer. Poly(vinyl alcohol) (PVA) has a wide range of applications in textile andadhesives, coating materials, fuel cells etc. Tensile measurements have shown peculiar behaviour of young modulus of PVA, with respect to the loading of SiC nanofiber. The aim of the proposed experiment is to investigate the effect of binding to SiC nanofiber on the dynamic of PVA and its correlation to the mechanical strength.
DOI: 10.5286/isis.e.rb1720147
title: Structural basis for the 2D thermal expansion tensor of petalite, LiAlSi4O10

description: Phases in the lithia-alumina-silica phase diagram (LAS) are of great importance owing to the technologically property of ultra-low thermal expansion (ULTE) that they frequently exhibit. Applications of these compounds range from oven-to-table cookware and cooker hobs to telescope mirror blanks and supersonic aircraft glazing. The most studied compounds have either the composition of spodumene or petalite and are formed by taking these materials to high temperatures at which point they undergo irreversible structural changes that gives rise to ULTE behaviour. Recently, an HRPD study has shown the compound petalite itself exhibits ULTE behaviour, ie not requiring high temperature sintering.We are proposing to understand the internal mechanism that permits ULTE behaviour in petalite by using single crystal neutron diffraction.
DOI: 10.5286/isis.e.rb1720172
title: Variable Temperature Neutron Study of Multi-Valley Band Te-doped Mg3Sb2-xBix Thermoelectrics

description: Thermoelectric (TE) materials are able to interconvert thermal and electric energy. To understand the promising Mg3Sb2-type TE materials produced in our lab, neutron diffraction data is necessary for us to fully examine and correlate the structure with their remarkable properties.The purpose of this proposal, therefore, is to explore the structure of Mg3Sb2-type TE materials (with Bi/Te) at ambient conditions and at high temperature using neutron diffraction. Furthermore, we will also examine and compare high temperature structure modifications when the sample is in powder and in dense pellet form. The need to pursue such a multi-faceted experimental regime is related to the applied nature of TE materials. Such materials have the potential to revolutionize the energy sector if we can optimize energy conversion efficiency, and generate dense products that are robust and reliable.
DOI: 10.5286/isis.e.rb1720176
title: Magnetic Properties of Functionalized Graphene

description: Recently, we have shown that if the graphene lattice is doped with sulphur, ferromagnetism can emerge once the doping threshold  level is overcome [10]. In particular, graphenes doped with 4.2 at.% of S showed strong ferromagnetic properties below ~62 K with a saturation magnetization reaching ~5.5 emu/g, which is among the highest values reported so far for any graphene-based system or even carbon-based (nano)material . Similar effects were also observed in N [11] and F/OH [12] functionalized graphene which show a weaker magnetization with respect to S. The investigation of this exotic magnetism with muons is of fundamental importance as, according to our past experience, µSR is the only technique allowing to inequivocally proof the onset of long range magnetic order carbon based materials.
DOI: 10.5286/isis.e.rb1720188
title: Hydrogen Diffusion in the Reactive Carbon Overlayer on a Fischer-Tropsch Catalyst

description: Fischer-Tropsch (FT) catalysts offer a route to the production of fuels and chemicals from synthesis gas, which has a number of sources. This reaction is likely to play a key role in the future as oil becomes less available. The catalyst itself evolves over time, with increasing deposition of carbon. The rate determining step in the reaction is the transport of hydrogen to the active site, through the carbon deposits. We wish to measure the diffusion rate of hydrogen to the active site using QENS on a model FT catalyst that has previously been used. This will represent the first attempt to measure diffusion to the active site of a non-zeolitic catalyst.