cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1720326
title: Muons for Energy Nanonics

description: In order to improve the performance of future energy devices, nano-structuring materials is one of the most promising routes. LiFePO4 is a commercial battery cathode material where nanostructuring is of specific interest due to its anisotropic crystal structure where the Li ion diffusion occurs in 1D channels. In this continuation of an earlier Muon experiment we propose to further study the microscopic Li ion diffusion in nano-structured LiFePO4 samples. With our synthesis protocol we are able to produce high-quality nano-platelets with different coatings and channel lengths below 15nm. This will allow us to obtain samples and study their Li ion diffusion with respect to the surface coating and the strain they form. The results will be correlated with our parallel studies of the surface phonon spectrum in the same samples acquired by inelastic neutron scattering.
DOI: 10.5286/isis.e.rb1720329
title: Segregation of Zwitterionic Surfactants in PVA Film and Influence of Compatibility

description: Migration and segregation of small molecules in complex polymer matrices is relevant to a huge range of industrial problems which we aim to address via a coordinated series of experimental, computational and theoretical methods in large EPSRC/Industry programme.  Here, we focus on the influence of surfactant hydrophobicity (via systematic alteration of alkyl chain length) and matrix hydrophilicity (via degree of hydrolysis of PVA resin).  Our proposed NR experiments will isolate these factors and measure the time dependent evolution of surfactant segregation.
DOI: 10.5286/isis.e.rb1720361
title: HC-polymer 3D-network conjugated by hydrocarbon-fluorocarbon core/shell aggregates in supercritical CO2.

description: For the last two decades, many polymers have been tested to increase CO2 viscosity for enhanced oil recovery. Unfortunately, HC-polymers were found to be inactive for the viscosity enhancement due to their poor solubility in supercritical CO2 (scCO2). A recent SANS study (RB1610015) found that unusual FC-HC amphiphiles without a headgroup formed HC-core/FC-shell cylindrical aggregates in scCO2. The elongated aggregates can play an important role to enhance solubility of HC-polymers in scCO2 and to advance the polymer 3D-network by wrapping and conjugating the polymers with HC-HC interaction and/or specific interactions like hydrogen bond. This proposal aims to find appropriate HC-polymer/FC-HC amphiphile mixtures for constructing 3D-network in scCO2. This SANS study will provide important information and enable the development of novel, EOR-oriented, CO2-thickeners.
DOI: 10.5286/isis.e.rb1500028
title: µSR investigations of multiband triplet superconductivity in a quasi-1D system: K2Cr3As3
DOI: 10.5286/isis.e.rb1510437
title: A molecular 2D quantum Heisenberg antiferromagnetic system diluted with non-magnetic impurities

description: Low-dimensional quantum magnetism continues to be of great theoretical and experimental interest, as reduced dimensionality supports strong quantum fluctuations which can result in novel excitations and critical behaviour. Here we propose to complete our investigation of a series of molecular 2D quantum Heisenberg antiferromagnets (2DQHAFs) with substituted non-magnetic ions. This is a continuation of experiment RB1320234, in which the pristine material and nominal 8% Zn-substituted system were measured. We have shown that muons are a powerful means of exploring the magnetic order and disorder in this system and we now seek to measure more diluted compounds with different Zn concentrations in order to complete our investigation of the phase diagram of this novel 2DQHAF.
DOI: 10.5286/isis.e.rb1520439
title: Unconventional superconductivity in quasi-1D K_2Cr_3As_3

description: Metallic systems with one-dimensional chain-like atomic structure can support unusual mechanisms for electron pairing leading to superconductivity. K_2Cr_3As_3 is one of a family of recently discovered one-dimensional superconductors which has a transition temperature of 6.1 K, a value nearly five times higher than that of (TMTSF)_2ClO_4, the most well-studied previous example of a 1D superconductor. This work will use a range of implanted muon techniques to measure key superconducting parameters of K_2Cr_3As_3 and test the nature of the unconventional superconductivity in this intriguing new system.
DOI: 10.5286/isis.e.rb1610029
title: The role of Ti-doping on hydrogen desorption temperature in LiAlH4 and NaAlH4

description: Fuel-cell cars are expected to be an ultimate solution for accommodating clean environments with convenient personal transport system. In order to make fuel-cell cars more compact and more accessible, we need to solve the problem how to store hydrogen in a limited space on board. At present, a high-pressure gas cylinder is used for such purpose. If such cylinders are replaced by an advanced hydrogen storage system based on solid state hydrogen storage materials, we will get more space in fuel-cell cars and shorter time for refill hydrogen in a hydrogen gas-station. For such purpose, we propose the muSR experiment on hydrogen storage materials, LiAlH4 and NaAlH4, to know the hint how to improve their hydrogen desorption temperature. This is because muSR provides microscopic information on solids through the change in the internal nuclear magnetism.
DOI: 10.5286/isis.e.rb1610199
title: Muon spin relaxation in the ferromagnetic superconductor UCoGe

description: Superconductivity near ferromagnetism, found in several U-based compounds, often exhibits intriguing superconducting properties. Recently, UCoGe was shown to belong to a new family of ferromagnetic metals. It is a weak itinerant ferromagnet below Tc=3 K and  becomes superconducting at Tsc=0.8 K. Spin-triplet superconductivity, which is a rare superconducting property, is suggested UCoGe. We propose to carry out ZF-MuSR experiments on single crystals of UCoGe to investigate the pairing mechanism of UCoGe.
DOI: 10.5286/isis.e.rb1610218
title: µSR Study of Topological Superconductor PbTaSe2
DOI: 10.5286/isis.e.rb1610310
title: Intrinsic defect structures in zinc oxide

description: Zinc oxide is an important semiconductor material used in a wide range of industrial applications, many of which require both n-type and p-type components. It can easily be doped n-type, but it is difficult to dope p-type. This has been attributed to the nature of its intrinsic defects, which cause a self-compensation of free carriers. It is, therefore, important to understand the nature of its intrinsic defects. There have been many first-principles calculations of the stability of intrinsic defects in zinc oxide. These theoretical predictions also give the local distortion of the surrounding lattice, and this can be tested directly using diffuse neutron scattering. We have large single crystals of as-grown nominally stoichiometric, oxidised and reduced zinc oxide, and we propose to measure the diffuse scattering using neutron Laue diffraction on SXD.
DOI: 10.5286/isis.e.rb1610369
title: Impact of Elasticity on Surface Wetting

description: We have recently characterised a surface wetting transition for a low molecular weight oligomer in a high molecular weight rubbery polymer.  Although weak surface segregation of low molecular weight compounds in polymers is known, the transition from a partial wetting layer to a thick wetting layer has received little attention.  This phenomenon is of significant practical importance as it governs on the surface physical properties of hot melt adhesive formulations.  In a parallel theory project, it has recently been established that the modulus of the elastomer material may also have a significant impact on the wetting behaviour, which in turn is of significant to the long term ageing and drying properties of hot melt adhesives.  This beamtime proposal will directly test the new theory by measuring surface segregation in which the modulus is controlled in-situ by crosslinking.
DOI: 10.5286/isis.e.rb1610418
title: A study of the role of divalent cations in the stability of smooth LPS in outer membrane models

description: The Outer Membrane (OM) is found in bacteria which cause plague, cholera & Legionnaires disease. It is important as; a barrier to antibiotics & the site of human-bacteria interaction. However bacteria are too small to allow us to do precise measurements of the structure and dynamics of this critical interface. Using neutrons as our eyes we have recently investigated OM models which imitate many aspects of the natural OM. This includes its structure where the outer surface is dominated by a molecule called lipopolysaccharide (LPS).  However the model is unstable if we use the very large versions of LPS found in some bacteria. This project aims to understand this by varying the ions that are known to stabilise the OM. In this way we seek to understand what maintains the structure of the natural OM and thus improve our future models.
DOI: 10.5286/isis.e.rb1620130
title: Characterisation of Protons in Pyrochlore Electrocatalysts

description: This proposal is about understanding the atomic-scale structure of complex oxides that contain water or protons and that are used as electrocatalyts for water splitting. Such materials are are highly sought after to meet the demands of energy applications, such as in electrolysers for hydrogen and oxygen production for clean fuels. We are exploring the formation of new oxides to optimise activity, in particular by hydrothermal synthesis, which allows a variety of metals to be included in nanocrystalline oxides that can be made into robust catalysts. To understand why some materials are better than others, we need to build up a comprehensive picture of their structures and to relate this to their synthesis conditions and electrocatalytic activity. The question to address here is the nature of protonic species in the oxides: this we will investigate by inelastic neutron scattering.
DOI: 10.5286/isis.e.rb1620397
title: Solving the antiferromagnetic structure of Gd3Al5O12.

description: This proposal would like to map the diffraction patterns of Gd3Al5Gd12 (GAG) using the high flux diffraction instrument WISH. It is of great interest to solve the magnetic structure of GAG in applied magnetic field and in particular in the antiferromagnetic (AF) region as defined by susceptometry. The magnetic structure in the AF region for the analogous compound Gd3Ga5O12 (GGG) has eluded clarification for over 20 years while the profile in GAG, obtained via recent measurement on LET, appears simpler. These measurements will determine the universal nature of exotic phenomena observed in GGG, namely the hidden multipolar order with its associated decagon spin loops that permeate the (H,T) phase space.
DOI: 10.5286/isis.e.rb1620410
title: Are magnetic excitations in the Yb based pyrochlores really gapless?

description: A recent neutron study of a powder sample attests a splayed ferromagnetic structure for Yb2Ti2O7. However in the same work the authors report gapless magnetic excitations even though a Hamiltonian deduced from spin wave excitations under applied magnetic fields supports gapped excitations and a ferromagnetic ground state. Given that the obtained magnetic order parameter in this sample strangely does not respond to the sharp heat capacity anomaly, questions about the quality of this sample as well as the interpretation of gapless magnetic excitations as a universal feature for the Yb based pyrochlores have been raised. We believe we have obtained a proper sample that can be used to resolve huge controversy regarding magnetic excitations of Yb2Ti2O7 at low temperatures by inelastic neutron scattering in LET. For comparison, we propose also the same study on a mysterious sibling, Yb2Ir2O7.
DOI: 10.5286/isis.e.rb1620412
title: Stationary Spin Waves in the Skyrmion Crystal

description: The inter-metallic B20 compound MnSi is of great interest as a magnetic model system exhibiting helical spin ordering and topologically non-trivial spin correlations. The application of a small magnetic field leads near TC = 29 K to the formation of a skyrmion crystal which is a 2D hexagonal lattice perpendicular to the applied field composed of magnetic vortices (skyrmions). These vortices are stable due to their topology and therefore of high technological interest in terms of data storage. In fact it was shown that it is possible to write, read and delete individual skyrmions in an ultra thin magnetic film. To understand this novel type of magnetic texture it is crucial to study the associated spin waves - the skyrmimagnons - as their dispersion directly reveals the underlying interaction parameters.
DOI: 10.5286/isis.e.rb1620431
title: Surface composition in the physical developer process for latent fingerprint visualization

description: Physical developer (PD) is a latent fingerprint development technique that is highly effective on paper and related surfaces, notably banknotes. The process exploits a redox reaction in which Ag(I) ions in solution are reduced by Fe(II), resulting in deposition of metallic silver on fingerprint residue on the surface. The standard formulation includes both a cationic and non-ionic surfactant, whose presence is critical to formulation stability and efficacy, but whose role is poorly understood. However, the surfactant adsorption can be expected to play a significant role. Here, we seek to extend our study from a successful initial experiment studying the cationic surfactant alone to understand the competitive nature of adsorption between the two surfactants on a silver surface using specular neutron reflectivity. The outcomes will guide optimization of the PD and derivative process.
DOI: 10.5286/isis.e.rb1700062
title: Sensing Sulphur Dioxide in Robust Porous MOF Materials via Simultaneous Microwave Dielectric Spectroscopy and Neutron Diffraction

description: We seek to develop new materials for sensing and removal of toxic gases (esp., SO2) and request 2 days on POLARIS to study the structural binding details and dielectric data simultaneously as SO2 is adsorbed in two stable MOFs. We will use our microwave frequency resonator sample environment and gas delivery system, which has been used previously with the POLARIS beamline. Microwave dielectric measurements, when correlated with other characterisation techniques offer an easy and non-destructive method for interrogating polar molecule sequestering as well as providing a deeper understanding of mechanisms for gas sequestration. This proposal will allow us to perform correlation studies that will enable the determination of the structural origins of changes in dielectric behaviour as SO2 molecules are bound within the MOF structure, insights into the mechanism of sequestration.
DOI: 10.5286/isis.e.rb1710240
title: Quasi-elastic neutron study of the organic cation dynamics in single-crystal CH3NH3PbI3, resolved in 3D reciprocal space

description: Solar cells based on a layer of halide perovskite have recently seen rapid increases in efficiency, with certified values in excess of 20%.  The prototypical material of this class is the methyl-ammonium-containing halide perovskite CH3NH3PbI3.  Very recently, the phase transitions and dynamic disorder of this structure, which has been extensively studied since the eighties, have come under renewed scrutiny, since they appear to be related to key photovoltaic performance parameters. Here, we propose to directly resolve the reorientation dynamics of the CH3NH3 molecule for the first time, via single-crystal quasi-elastic neutron scattering resolved in 3D reciprocal space, on OSIRIS as a continuation of a previous experiment. This will allow the detailed study of the CH3NH3 reorientation and its effect on the phase transitions and symmetry of the low temperature phases.
DOI: 10.5286/isis.e.rb1720014
title: Proton Conductivity in Phosphoric Acid: The Role of Nuclear Quantum Effects.

description: We propose to employ the neutron Compton scattering (NCS) in the realm of ionic liquids (iL), applying it to the protiated and deuterated variants of an archetipic IL, phosporic acid (PA). PA and its solutions have one of the  highest  intrinsic  proton  conductivities among known materials, and  the mechanism of this unique conductivity remains a puzzle. A recent study discovered a strong isotope  effect in the conductivity: (i) a strong isotope shift of the glass transition temperature and (ii)  a significant reduction of the energy barrier by zero-point quantum fluctuations. These results  suggest that the high conductivity in phosphoric acids is caused by a very efficient proton transfer mechanism, which is strongly assisted by quantum effects. We propose  to measure two samples: (i)  85%  wt%  H3PO4  in H2O,  and (ii) D3PO4  in  D2O between 10 and 300K.
DOI: 10.5286/isis.e.rb1720216
title: INS Studies of Porous Metal-Organic Framework Materials for High Capacity Gas Adsorption

description: We seek to develop highly robust MOF materials as high capacity gas storage systems and request 12 days on TOSCA to study the binding interaction between adsorbed gas molecules (CO2/C2H2/C2H4/C2H6/C3H6/C3H8) and three isostructural MOFs  incorporating different functional groups as a function of gas loading. This proposed study will investigate the vibrational properties exhibited by both adsorbed gas substrates (except for CO2 due to the low neutron scattering cross sections) and the porous hosts. MFM-102-NO2 exhibit exceptionally high storage capacity for CO2 and light hydrocarbons at ambient conditions with fully reversible uptake, suggesting the presence of specific guest-host interaction.
DOI: 10.5286/isis.e.rb1800019
title: Investigating the Effect of Structural Rigidity on the Electromechanical Response of Ionic Triblock Copolymers

description: One of the rapidly developing frontiers in research is focused on the rational design of polymeric materials that have targeted functionalities and tunable responses to external stimuli. A chief obstacle to achieving this capability is the lack of a fundamental understanding of how chemical structure and morphology give rise to macromolecular properties. Considering this, the research proposed here aims to investigate how polymer structure and counterion identity affects the electromechanical response of materials when exposed to external electric fields. Our previous results have confirmed that neutron reflectometry is an ideal tool for monitoring the motion of both the polymer backbone and counterions. This proposal builds on those findings and will focus on understanding how film rigidity and counter-anion size restricts or enhances the system response to an applied electric field.
DOI: 10.5286/isis.e.rb1800021
title: The crystal structure of multiferroic CuO

description: Despite its simple chemical formula, cupric oxide (CuO) has a surprisingly complex magnetic behaviour which remains only partly understood. Interest in CuO has recently resurfaced with the discovery of a magnetically-induced multiferroic phase at high temperatures. Neutron scattering has revealed that the multiferroicity is accompanied by a change in the magnetic structure from a commensurate antiferromagnet at low T, to an incommensurate helical structure in the multiferroic phase. We have investigated the spin dynamics and magnetoelectric behaviour in CuO, to understand the mechanism that drives the multiferroic phase. We have recently measured the complete spin-wave spectrum throughout the Brillouin zone, but we have found that the data cannot be modelled within the symmetry imposed by the published crystal structure. We therefore wish to use HRPD to determine the structure of CuO.
DOI: 10.5286/isis.e.rb1800038
title: Jahn-Teller distortions in uranium compounds: Powder Neutron Diffraction

description: The magnetic behaviour of actinide complexes are of interest as these show unusual physics that relate to single molecule magnet behaviour. We have studied the magnetic behaviour of U(IV) compounds where we can control the geometry whilst keeping the same ligands - this has not been reported in the literature for any f-block metal complex. Computational investigations have shown that [Et4N]4[U(NCS)8], which has a RT cubic geometry, may show a Jahn-Teller distortion at low temperatures; this may explain the results we obtained from Inelastic Neutron Scattering experiments. To probe this in detail we measured to X-ray structure at 4K and there was evidence of a distortion but as the uranium dominates the diffraction, this was not conclusive. Single crystal neutron diffraction does show a distortion but the results need powder diffraction to confirm this. This is the objective of this work.
DOI: 10.5286/isis.e.rb1800040
title: A-site vacancies in La-substituted SrTiO3: Local Ordering and Relaxations

description: Reduced Sr1-xLa2/3xTiO3 ceramics, which crystallize with distorted perovskite structures, attract interest as promising high-temperature thermoelectrics.  Developing structure-properties relations in these solid solutions requires knowledge of their local atomic arrangements, including those associated with A-site vacancies.  Despite multiple studies of the average structures in La-substituted SrTiO3, quantitative information on the vacancy distributions and the related structural relaxations is currently missing.  The present study aims to fill this gap.  We plan to determine the local structures in Sr1-xLa2/3xTiO3 using a combined input from neutron and x-ray total-scattering data, EXAFS, and atomic-resolution TEM images.   The goal of the proposed experiments is to provide the neutron total scattering data for such local-structure refinements.
DOI: 10.5286/isis.e.rb1410394
title: In-situ neutron diffraction studies of LiCoO2 cathode material for Li-ion batteries

description: LiCoO2 as cathode for Li-ion batteries suffers from a large capacity fading after extended cycling.  The ordered structure (Li+ and Co3+ atoms occupy alternate (111) layers of the rock salt structure) undergoes several phase transitions during charge which cause structural degradation of the material. In fact, the structural stability of Li1-xCoO2 is maintained only for a limited compositional range 00.5. This is attributed to the structural transition from a hexagonal to monoclinic phase. In order to monitor the phase transitions in LiCoO2 as a function of charge/discharge, we plan to use the new in-situ cell especially designed for Polaris.We expect to conduct Rietveld refinement for the LixCoO2 phases as a function of x and extract relevant structural information by Rietveld refinement.
DOI: 10.5286/isis.e.rb1510097
title: QENS studies of hydride ion diffusion in alkaline earth hydrides

description: We propose to study hydride ion diffusion in AEH2 (AE = Ca and Ba) using the QENS technique. We have recently demonstrated that the charge carrier in these materials are hydride ions (H-). A previous neutron study employing the new high temperature and conductivity sample environment jointly developed by ISIS and the University of St Andrews for use in ISIS diffractometers further strengthened the case (RB1410181), and QENS will supplement these studies with quantitive data on diffusion mechanistic steps. QENS has been used extensively to study the diffusion of ions in solids. More specifically, proton and hydride ion diffusion have been studied to elucidate diffusion (and conductivity) mechanistic steps such as average ionic jump distances and frequency as well as jump positions.