cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1610100
title: Why is CaLn2Ni2WO9 (Ln=La, Pr, Nd) not a relaxor ferromagnet?

description: La3Ni2SbO9 exhibits relaxor ferromagnetic behaviour in an analogous way to relaxor ferroelectrics. To investigate the effect of competing magnetic interactions and subtle differences in the crystal structure on this novel ground state we synthesised CaLa2Ni2WO9, CaPr2Ni2WO9 and CaNd2Ni2WO9 for the first time.  None of these compounds displayed the relaxor ferromagnetism of La3Ni2SbO9 and we need to understand why relaxor ferromagnetic behaviour is not observed. We request two days on WISH to collect data on all three compounds at room temperature and at 4K and to collect additional data at 20K on CaNd2Ni2WO9 to elucidate the nature of any magnetic ordering and to refine accurately their crystal structures.
DOI: 10.5286/isis.e.rb1610144
title: Stress gradient investigation of Fe-based materials prepared by Selective Laser Melting

description: Selective Laser Melting (SLM) has a great industrial potential since it enables, from metal powder beds, producing full density complex monolithic part. The high temperature gradient resulting from the locally concentrated energy input leads to strong temperature fields driving to residual stress gradients, cracks formation and part deformations. Resulting stress and texture gradients arise from the interdependent physical phenomena (metallurgical, thermal, mechanical and fluid mechanics aspects) occurring during the process and the different thermal environment and surrounding thermal history of the considered position. Present proposal focus on the residual stress being built in two SLM-prepared Fe-based alloys with having different mechanical properties in order to provide the comprehensive data set needed to develop more realistic multiscale thermomechanical Finite Elements model.
DOI: 10.5286/isis.e.rb1610285
title: The structure of formamidinium lead iodide between 10 and 450 K

description: The recently discovered hybrid lead iodide materials have captured significant attention due to their application in highly efficient solar cells. The fact that these materials may be deposited from solution may lead to cheap printable solar cells. While most attention originally focussed on methylammonium lead iodide recent  record high efficiency cells have used a different organic cations - formamidinium. In this experiment we will study the structure of formamidinium lead iodide over a large temperature range to investigate how the organic cation interacts with the inorganic lead iodide part structure.An understanding this interaction, and coupling it with computational modelling, is central to understanding the way in which these materials absorb sunlight and convert it into electricity
DOI: 10.5286/isis.e.rb1610404
title: Lithium Insertion Sites of Ramsdellite TiO2

description: TiO2  based materials have potential applications as anodes in rechargeable lithium-ion batteries. TiO2 possesses several advantages over other oxide anode systems due to it having a low cost and being environmentally benign.  There are several different structure types of TiO2, but in particular the ramsdellite form remains relatively unexplored with respect to Li intercalation.  Our recent electrochemical studies have suggested that there may be as many as 6 to 7 lithium sites when ramsdellite TiO2 is lithiated.  We propose to study the structure of these LixTiO2 materials at room temperature, in order to gain accurate lithium positions, temperature factors and site occupancies, which will help understand the structural parameters that are responsible for the interesting electrochemical behaviour.
DOI: 10.5286/isis.e.rb1610505
title: Spin excitations in the single layer half doped manganite Pr0.5Ca1.5MnO4 above the Neel temperature

description: The ground state of the single layer half-doped manganite Pr0.5Ca1.5MnO4 has the canonical CE antiferromagnetic charge- and orbitally-ordered (CO-OO) structure characteristic of so many half-doped manganites.  We have just measured the full spin wave dispersion in the ground state, and now propose to measure (1) above the 3D ordering temperature T_N = 130K but below the charge-and orbital ordering temperature T_CO=320K, and (2) above T_CO. The spins form one-dimensional magnetic chains which are relatively weakly coupled. The goal is determine how the loss of long-range magnetic order and then also orbital order alters the 1D spin dynamics; one feature we propose to look for is possible dimerisation of Mn spins along the chain.
DOI: 10.5286/isis.e.rb1620042
title: Electron localisation in vanadium hollandites

description: Hollandites (AxM8O16, where A is a large cation and M is a transition metal, here vanadium) have been studied for a wide range of properties, including electronic phenomena such as metal-insulator transitions (MIT).  We are currently investigating BixV8O16 and BixBayV8O16 materials showing electronic transitions that may correspond to the formation of orbital molecules (small clusters of metal-metal bonded transition metal ions in orbitally ordered states). For BixV8O16 compositions, a MIT has been observed but no low temperature structural work was reported.  The high resolution of HRPD is essential to determining accurate crystal structures in these materials. Neutrons are required to determine accurate oxygen atom positions, essential for characterising charge and orbital orders.
DOI: 10.5286/isis.e.rb1620089
title: Chemical control of structures and magnetic ordering of manganese oxide chalcogenides

description: We will probe the response of the magnetic and crystal structures of layered manganese oxide chalcogenides to the oxidation state and the local coordination environment of Mn. This will enable us to build up a clear picture of the complexity in these phases and will provide experimental data to enable us to rationalise the origin of the competing magnetic ground states in this series of compounds.
DOI: 10.5286/isis.e.rb1620305
title: Non-centrosymmetrtic Dion-Jacobson and Ruddlesden-Popper Phases

description: Ferroelectric materials find many applications, however ferroelectric behaviour is rare as it requires a material to have a non-centrosymmetric (NCS) structure.We have been studying the role of the cooperative twisting and tilting distortions of the octahedral units in layered Dion-Jacobson and Ruddlesden-Popper phases on NCS structure formation. DFT calculations predict that the ground state structures of ANdB2O7 (A = Cs, Rb; B = Nb, Ta) phases should be polar. SHG measurements have confirmed these phases have acentric crystal structures.Furthermore, the large A cations in Dion-Jacobson phase can be exchanged for lithium, to yield phases with Ruddlesden-Popper type structures. SHG measurements indicate these phases are also acentric. We propose to collect powder neutron diffraction data from these phases to determine their structures accurately.
DOI: 10.5286/isis.e.rb1620334
title: Thermal expansion and ordering in D2O ice III / IX

description: The high-pressure form of solid water, ice III, is the equilibrium phase in contact with liquid water at pressures from about 2.0 - 3.5 kbar. Consequently, its properties are important in calculating the volume changes on freezing of subsurface oceans inside icy planetary bodies and the buoyancy of icy volcanic melts. The incompressibility (bulk modulus) of ice III as found by quantum mechanical simulations is much lower (&lt;60%) than that of the other ice phases at neighbouring pressures and temperatures, but it is not known whether its thermal expansion is similarly "anomalous". We shall use HRPD to investigate metastable ice III (= ice IX, when proton ordered) by high-resolution neutron powder diffraction so as to determine both its thermal expansion and, from accurate structure refinements, the extent of proton ordering in its crystal structure.
DOI: 10.5286/isis.e.rb1710038
title: Hydration of osmolites

description: Knowledge of the hydration of small osmolytes can challenge the "preferential exclusion" model hypothesized to explain their action as bio-protectant against osmotic stress. This model is based on the assumption that osmolyte-water interactions are stronger than osmolyte-osmolyte ones. Available neutron diffraction data on aqueous solutions of other osmolytes (as glycine and proline) and of sugars (as trehalose) do not seem to confirm this  interpretation. In order to gain better knowledge of the balance solute-solute and solute-solvent interactions at the atomistic level in this class of small bio-molecules, we propose to perform NDIS experiments on aqueous solutions of ectoine and trimethylglycine. The former has been chosen in order to compare with the recent SANS results, the latter because it has much weaker solute-solute interactions than glycine.
DOI: 10.5286/isis.e.rb1710342
title: Association and liquid structure of zwitterionic salts-water mixtures

description: Anti-fouling surfaces are a critical requirement for a wide range of biomedical applications, such as medical implants and biosensors. Poly(ethylene glycol) is widely used despite some serious drawbacks such as susceptibility to oxidation. Zwitterionic polymers have been recognised as promising alternatives with higher chemical stability, effectiveness to resist biofouling, and better long-term performance. The higher resistance of polymeric zwitterionic materials has been explained in terms of the greater electrostatic hydration of charged zwitterionic terminal groups compared to PEG. New zwitterionic salts (ZWSs) that consist of a cation and an anion, with an additional zwitterionic moiety embedded in either the cation or the anion, have even greater larger hydration shells and stronger interactions with water and may leading to enhanced anti-fouling characteristics.
DOI: 10.5286/isis.e.rb1720292
title: Dynamics of amyloid protein fibril elongation using isotope-labelled SANS

description: This proposal combines small-angle neutron scattering with novel labelling strategies to investigate amyloid protein fibrils. Variations in packing and in the dynamics of elongation and breakage underpin phenomena ranging from non-genetic heredity in yeast, to diseases such as Alzheimers, BSE and CJD. Most solution methods to monitor growth dynamics only give information on the overall % of material transformed from non-fibrillar to fibrillar forms. They cannot determine length distribution or linear growth rates, but instead convolute the two; in other words, they cannot distinguish a few long fibrils each growing quickly, from many short fibrils each growing more slowly. We will determine both fibril lengths and linear growth rates using a novel SANS approach with labelled ends growing on contrast-matched "seed" fibrils
DOI: 10.5286/isis.e.rb1800066
title: When like-charged ions attract: Size and distribution of cationic clusters in ionic liquids

description: Contrary to the strong electrostatic repulsion between like charged ions, last year the Ludwig group, used IR and NMR spectroscopy combined with computational methods, to reveal cation  cation (c-c) cluster formation at room temperature for ILs with 1-(2-hydroxyethyl)-3-pyridinium [HOC4Py] cations. c-c clusters cations form due to hydrogen bonding between the alcohol groups that terminate the cation alkyl chains.  This study will probe the liquid nanostructures of two ionic liquids, [HOC4Py] NTf2 and [C5Py]NTf2, which are identical except that the alkyl chain of the former is terminated by OH and the latter by CH3. Hence, ion clustering is expected in [HOC4Py] NTf2 but not [C5Py]NTf2. We will determine the most probable cluster structures, provide details on ion packing, and perform quantitative cluster analysis on these systems for the first time.
DOI: 10.5286/isis.e.rb1810289
title: Exotic spin excitations in a quasi one-dimensional anisotropic Heisenberg magnet

description: Very recently, string states have been identified for the first time in antiferromagnetic Heisenberg-Ising chain SrCo2V2O8 in longitudinal magnetic fields using high-resolution terahertz spectroscopy. Instead of string states, another exotic excitations called psinon/(anti)psinon pair excitations have also been identified in the critical field regime and both novel excitations can be described by the Bethe ansatz. However, due to the intrinsic limits of the terahertz spectroscopy, the momentum dependences of these novel excitations are still elusive. The primary goal of this proposal is to identify string states and psinon/(anti)psinon pair excitations using inelastic neutron scattering technique. The spin excitation spectrum in the full Brillouin zone would be mapped out and the momentum dependences of the spin excitations would be determined.
DOI: 10.5286/isis.e.rb1810290
title: Interface induced magnetization in LSMO/BFO heterostructures

description: Recently multiferroic materials have been studied for possible potential application in next-generation information technologies and systems, which possess a higher memory speed and density with lower energy consumption. There are many multiferroic materials but BiFeO3 (BFO) is the most studied multiferroic material due to its room-temperature multiferroic properties. Similarly La0.67Sr0.33MnO3 (LSMO) is perovskite manganites which exhibit fascinating properties at room temperature such as half metallicity and colossal magnetoresistance (CMR). We propose to perform low temperature polarized neutron reflectivity (PNR) measurements on BFO/LSMO system grown on MgO substrate to investigate the depth dependent magnetization in this system.
DOI: 10.5286/isis.e.rb1810351
title: Improved detection limit of hydrogen in materials using VESUVIO

description: The detection of hydrogen content in bulk media is a challenging task. Several techniques aiming at measuring  the amount of hydrogen require disruption or erosion of the sample. A suite of non-invasive techniques as broad as possible is often needed for bulk samples, and applications to cultural heritage. Electron-Volt neutron spectroscopy is a non-destructive technique for direct counting of hydrogen atoms owing to its mass-resolved nature. Recent experiments on the VESUVIO spectrometer showed the possibility to improve the count rate by modifying the detection procedure, namely lowering the energy threshold for detection of photons on the forward scattering detectors. Our aim is to optimise the hydrogen sensitivity by changing such threshold, and define a new limit of detection.
DOI: 10.5286/isis.e.rb1810739
title: The dynamics of water in halloysite nanotubes

description: Water is important in many scientific and technological areas, yet our understanding of this remarkable liquid remains very incomplete. In may cases, it is the properties of water at a surface or interface, rather than in the bulk, that are the key to the system's overall behaviour. There are many diverse examples where this is the case, ranging from protein folding to the uptake of water by soils. In this experiment, we will use the unique powers of neutron scattering to measure the dynamics of water in a particular type of clay mineral, known as halloysite. Halloysite is remarkable in this context, because it occurs as nano-scale tubes, which are formed from rolled-up scrolls of the clay sheets (like a swiss-roll, where a single molecular layer of water is the jam, and the clay sheet is the sponge-cake). Our expeirments will allow us to study water structure under extreme confinement.
DOI: 10.5286/isis.e.rb1820413
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 40 mole% of methane. This proposal is for neutron time to study the structure of this remarkable liquid/fluid.
DOI: 10.5286/isis.e.rb1868023
title: Neutron diffraction study of the structures and magnetic properties of Halden like spin chains in Layered Li3Cu2SbO6

description: A large variety of exotic magnetic structure and relevant magnetic properties is observed in honeycomb layered oxides. Recently Koo et al. showed two magnetic contributions i.e. quasi-free spins at low-temperature and a spin-gapped magnetic subsystem in Li3Cu2SbO6. Static magnetic susceptibility and ESR data suggest ferromagnetic-antiferromagnetic alternating chains with JFM = -285 K and JAFM = 160 K with a significant amount of Li-defects in the chain. There are about 0.8 quasi-free spins S = ½ per formula unit which cannot be explained by Cu2+ ions residing on Li position.  Susceptibility data fails to determinant the small difference between AFM-AFM alternating chains and AFM-FM ones with dominant ferromagnetic coupling. It is crucial to investigate low temperature magnetic structure using neutron diffraction measurement using WISH spectrometer in Li3Cu2SbO6.
DOI: 10.5286/isis.e.rb1520051
title: Phonon dispersions in CDW material Na2Ti2Sb2O

description: Na2Ti2Sb2O has a CDW transition around 120 K . It has a tetragonal structure with alternate layers of Ti2Sb2O2- and Na+ double layer. Interestingly, the Ba1-xNaxTi2Sb2O system exhibits superconductivity with a maximum Tc of 5.5 K. It is demonstrated that the Fermi surfaces around Gama and X can only overlap with each other with several points,clearly ruling out the Fermi surface nesting as the main source of the CDW transition.On the other hand, a very strong renormalization of the electron mass is found at the CDW wave vector (0.5,0.5), suggesting the presence of very strong electron phonon coupling in this system.  In 2H-NbSe2, it has been shown that acoustic phonons soften to zero frequency and become overdamped over an extended region around the CDW wave vector. Similarly, we propose to study the phonon dispersions in Na2Ti2Sb2O and the origin of the CDW phase in this material.
DOI: 10.5286/isis.e.rb1520090
title: Low energy spin dynamics of the stoichiometric heavy fermion CeRuSn3

description: Heavy fermion systems situated close to a quantum critical point present very rich physics due to the dominant Kondo interactions. Our investigations on the Kondo lattice heavy fermion CeRuSn3 reveals evidence of an untuned quantum criticality where the physics is governed by Griffiths singularities. The magnetization, magnetic susceptibility and heat capacity show clear power-law behavior indicating the formation of quantum Griffiths phase. The divergence of magnetic Grüneisen ratio and time-field scaling of longitudinal field µSR data reveals close proximity to a clean quantum critical point. Further investigations of untuned quantum criticality in stoichiometric CeRuSn3 by low energy spin dynamics study of E/T scaling would be very informative. We therefore propose to carry out E/T scaling study using low energy inelastic neutron scattering measurements on the OSIRIS spectrometer.
DOI: 10.5286/isis.e.rb1520349
title: Nuclear and magnetic structures at the morphotropic phase boundary in the magnetic ferroelectric [1-x]BiFeyTi(1-y)/2Mg(1-y)/2O3  [x]CaTiO3

description: We are investigating the design and synthesis of new Pb-free ferroelectrics that also offer long-range magnetic ordering at high temperatures by appropriate compositional tuning, opening a door to new ?multiferroic? materials that could underpin a new generation of data storage devices. We propose to characterise the nuclear and magnetic structures of a new series of magnetic ferroelectrics, [1-x]BiFeyTi(1-y)/2Mg(1-y)/2O3 ? [x]CaTiO3, which will allow us to rationalise and control the key functional properties (switchable polarisation, spontaneous magnetisation and magnetoelectric coupling) offered by this system at room temperature.
DOI: 10.5286/isis.e.rb1610058
title: Role of acidic silanols and Brønsted acid sites in hierarchically porous SAPO-34 for the production of eta-caprolactam - MAPS

description: The commercially important polymer Nylon 6 is manufactured by ring-opening polymerization of eta-caprolactam. Industrially, eta-caprolactam is conventionally made by the Beckmann rearrangement of cyclohexanone oxime, a stoichiometric process that generates large quantities of undesirable by-products. Recent work at Southampton has shown that a hierarchically porous silicoaluminophosphate; HP-SAPO-37, is able to achieve near-quantitative yields of eta-caprolactam at temperatures as low as 130 °C. The interaction of the oxime with acidic silanols and Brønsted acid sites is crucial to the mechanism but this is not well-understood. The aim of this proposal is to investigate a series of catalysts with different types of acidity in order to characterise how the interaction of cyclohexanone oxime varies with the different acid groups and hence provide insight into the reaction mechanism.
DOI: 10.5286/isis.e.rb1610095
title: Topochemical fluorination of n = 2 Ruddlesden-Popper phases

description: Low-temperature fluorination of A3B2O7 layered oxides allows the preparation of A3B2O7F2 oxide-fluorides in topochemical reactions that conserve the crystal structure of the original material. We are interested in materials prepared in this way for two reasons. Firstly the insertion of fluorine oxidizes materials, lowering their electron count and modifying the electronic and magnetic behaviour of the phase. Secondly the insertion of fluorine drives small distortions to the structure of the host phase which can break the inversion symmetry of the crystal structure and induce ferroelectric behaviour  a highly desirable physical property. We propose to collect high-resolution neutron powder diffraction data from a number of topochemically fluorinated phases to study the effect of fluorine insertion on both the crystal and magnetic structures of these materials.
DOI: 10.5286/isis.e.rb1610101
title: Lipodepsipeptides and Brown Blotch Disease in Mushrooms (i) Effect of biogenic amines

description: Tolaasin is a lipodepsipeptide (lipo = hydrophobic side chain, depsipeptide is an amino acid ring closed in a particular way) produced by strains of Pseudomonas tolaasii, and it causes Brown Blotch disease in mushrooms. This is a major problem in commercial mushroom growing. Tolaasin is detected by the formation of a "white line" when it comes into contact with the lipodepsipeptides, WLIP (White Line Inducing Peptide) created by Pseudomonas reactans. WLIP is evidently antagonistic to tolaasin but the mechanism is not understood. White line formation is enhanced by the biogenic amine, octopamine. Preliminary reflection experiments confirm a strong specific interaction of octopamine and WLIP. This seems to require an unfolding of the known solid state structure of WLIP and we propose to determine the layer structure using reflectometry and part deuterated WLIP.
DOI: 10.5286/isis.e.rb1610172
title: Unraveling the crystal structure of cuprice, CuOH×H2O SANDALS

description: Long-term nuclear waste repository strategies in Europe include the developing of safe multi-barrier isolation of spent nuclear fuel. One of the considered schemes is the sealing of nuclear waste into Cu canisters that are then stored in bedrock. Assuring the stability of Cu in a radioactive environment  specifically, exposure to ground water  requires an understanding of the processes happening at the Cuwater interface under radiation and knowledge about compounds that Cu forms with O and H. CuOH is a by-product of the radiation-induced degradation of Cu in water. It is one of the less studied Cu(I) compounds, there is no information about its structure. Neutron diffraction experiments at ISIS will help to determine the positions of light elements and solve the structure of CuOH, and thus help our understanding of the process of radiation-induced degradation of Cu in water.