cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1720369
title: Temperature-dependent crystal structure analysis of new pyrochlore ruthenate In2Ru2O7

description: In search for new materials with exotic electronic states, one often turns to strongly correlated materials. Ruthenium oxides attract attention as they exhibit intriguing phenomena such as unconventional superconductivity, metal-to-insulator transition or complex spin-orbital order. We synthesised a new pyrochlore ruthenate In2Ru2O7, which at 232 K shows a suppression of magnetisation to nearly zero. This behaviour is similar to some other ruthenates where spin-singlet formation appears by accompanying a structural transition. X-ray diffraction shows symmetry lowering with decreasing temperature. In order to understand the transition and the ground state in this material, detailed structural data is necessary. However, determination of oxygen positions by X-ray diffraction remains elusive. We would like to investigate the structural transition using powder neutron diffraction at HRPD.
DOI: 10.5286/isis.e.rb1800103
title: Testing of Latching Current Limiters for Single Event Effects

description: As part of the activities relating to the TRISAT project, we have developed an approach to designing SEE tolerant electronic circuits by using COTS components. The approach consists of the use of basic analogue parts that is then coupled with of a careful component selection in combination with an FPGA circuit, enabling various miniaturized complex circuits to be produced. We have applied this approach in the design of three different kinds of LCLs (Latching Current Limiters), each with a different set of functionalities. By testing the LCLs and the FPGA control circuits for SEE effects, we would like to show that the design approach we used is suitable for producing SEE tolerant electronics. We already performed proton beam tests and have found no occurrences of SEE effects - by performing a similar test with a neutron beam, we would further strengthen the confidence in the design.
DOI: 10.5286/isis.e.rb1810112
title: Vibrational property analysis of NH4BH4 using inelastic neutron scattering

description: The proposed experiment at ISIS aims at the characterization of the vibrational properties of ammonium borohydride, NH4BH4, which possess the highest gravimetric H density (~25 wt.%) of any chemical compound. The H disordered crystal structure is composed of the tetrahedral complex ions NH4+ and BH4-. Recent investigations revealed the presence of dynamic disorder, corresponding to very rapid reorientation of both ions, in the temperature range 100  250 K. The elucidation of the vibrational properties of NH4BH4 from INS spectroscopy will give new fundamental understanding of dihydrogen bonding in boron-nitrogen based hydrides. It particular this concerns successive ordering processes which are expected to take place below 100 K. These should reveal from the temperature dependence of the internal modes and the possible presence of librational modes of the tetrahedral complexes.
DOI: 10.5286/isis.e.rb1810245
title: Vibrational property analysis of a series of metal borohydride ammonia inclusion compounds using inelastic neutron scattering.

description: The proposed experiment at ISIS aims at the characterization of the vibrational properties of the series of coordination complexes Pr(BH4)3nNH3, n = 4  7. The systematic variation in the number of ligands triggers changes from ionic to molecular structures which in turn influences decisively dihydrogen interaction between partly positively charged hydrogen, Hδ+, bonded to N and partly negatively charged hydrogen, Hδ−, bonded to B. It is hoped that INS spectroscopy will give new fundamental understanding of dihydrogen bonding in boron-nitrogen based hydrides.
DOI: 10.5286/isis.e.rb1810348
title: Understanding Molecular Host-Guest Interactions in Functionalised Metal-Organic Frameworks (Guest@MOF) via Inelastic Neutron Scattering

description: We aim to perform inelastic neutron scattering (INS) measurements at the TOSCA spectrometer to study the vibrational behaviour of designer Guest@MOF composite systems (e.g. Pd@OX-1 and ZnQ@OX-1) that we recently developed. The key objectives are as follows: (i) To characterise the precise nature of the vibrational dynamics underpinning the Guest@OX-1 composites compared to the vacant OX-1 host compound (no guest in its pore). (ii) To understand how the vibrational dynamics of the host can be modified upon confinement of bulky guest species, such as Pd or ZnQ complexes. (iii) To study the salient modification to the THz dynamics of the host framework as a function of temperature to elucidate tuneable host-guest molecular interactions of bespoke Guest@MOF composites.
DOI: 10.5286/isis.e.rb1810480
title: Magnetic Structure of Low Temperature Phase of UAu2

description: UAu2 has an exceedingly simple crystalline structure comprised of columns of U arranged in a triangular lattice, raising the prospect of magnetic frustration. There is a clear transition to a modulated incommensurate antiferromagnetic state at 43K. However quantum critical behaviour is then seen in the macroscopic properties below 20 K, well within the ordered state. Such behaviour is unprecedented. It is considered to be brought about by the frustration inherent in the triangular lattice preventing the squaring up of the modulation. A second transition then exists at 420 mK from the quantum critical state to a strongly correlated Fermi liquid like state. We would like to determine if this second transition is accompanied by a change in the magnetic structure and hence if the magnetic frustration is solely responsible for the measured quantum critical behaviour.
DOI: 10.5286/isis.e.rb1810668
title: Direct measurement of the nuclear momentum distribution in a switchable dielectric framework

description: The family of hybrid Prussian blue analogues includes many electroactive materials, where organic cations moving within the pores of the cyanide framework cause unusual and exploitable electrical properties. Our target material, (HIm)2K[Fe(CN)6], undergoes a phase transition associated with a dramatic decrease in dielectric constant on cooling, as the imidazolium ions stop rotating and freeze into position. The local dynamics in the high-temperature phases remain poorly understood; but it is precisely these that we will need to control in order to engineer new materials in this family with desirable properties. We therefore propose to measure the nuclear momentum distribution for each element in this sample via DINS measurements on VESUVIO. Our results will help to elucidate the link between the motion of the imidazolium cations and the material's dielectric switching.
DOI: 10.5286/isis.e.rb1820009
title: Equation of state and phase transitions of the cubic NTE material Cd(CN)2 - continuation

description: Cubic cadmium(II) cyanide shows the most pronounced isotropic negative thermal expansion (NTE) effect known, with behaviour more than twice as extreme as that of better known materials such as ZrW2O8. Because NTE is driven by soft phonons, it is possible to gain important mechanistic insight from the structural response of Cd(CN)2 as a function of both temperature and pressure. This experiment is a continuation of a previous experiment on HRPD which showed promising results: we identified at least two new high-pressure phases, but were unable to solve these due to high absorption of the pressure cell. This study aims to resolve these outstanding questions by exploiting the high flux and high resolution in relevant banks available on Osiris. It forms an important part of Chloe Coates's DPhil project as she is in her final year.
DOI: 10.5286/isis.e.rb1820173
title: Unravel Stabilization Mechanism of CO2 Foams under High Temperature and High Pressure with HP-SANS

description: Long-term stable CO2 foams were generated under high temperature (120 ºC) and high pressure (12 MPa) (HPHT) in our laboratory using a C22-tailed weak cationic surfactant, N-erucamidopropyl-N,N-dimethylamine (UC22AMPM), as the stabilizer. We hypothesize that the enhanced CO2 foam stability under HPHT was possibly attributed to the high bulk phase viscosity and interfacial viscosity resulted from the wormlike micelles (WLMs) formed from UC22AMPM molecules inside the wet foam film. Thus we request beam time of high-pressure small-angle neutron scattering (HP-SANS) to check the existence of such WLMs residing on the foam liquid channels under different temperature and different pressure.
DOI: 10.5286/isis.e.rb1820299
title: Preferential Conduction Pathways in Sodium Conducting Glasses for Battery Applications

description: The ionic conductivity of sodium chalcogenide or chalcohalide glasses is 2 to 3 orders of magnitude higher than that of oxide glasses and comparable with lithium ionic conductivity. This makes sodium chalcogenide systems suitable for applications in power rechargeable systems. More importantly, the sodium batteries appear to be a good alternative to lithium systems extensively used in everyday life but limited by the fact that lithium is not an abundant element.  In order to understand the relationship between the glass local and intermediate-range structure and the ionic transport, we are going to combine diffraction and spectroscopy measurements of sodium sulphide and selenide glasses with conductivity and diffusion studies, as well as structural modelling using DFT.
DOI: 10.5286/isis.e.rb1820343
title: Modelling Intermolecular Interactions and Thermodynamic Properties of Naphthalene at High Pressure

description: Equations of state (EoSs) show how the thermodynamic variables of temperature, pressure and volume are inter-related.  The ideal gas law, PV = nRT, is an example of an EoS which is used as a simple but effective model to explain the properties of gases.  EoSs can also be applied to solids, where they can be used to show how energy changes when the solid experiences dramatic changes in its environment, which occur for example on the surfaces of planets and their moons.  In this beamtime we will derive the EoS of naphthalene, a simple model for the polyaromatic hydrocarbons which are thought to be the repository for most of the carbon in the Universe. The results will be used to reveal the changes in different contributions to the thermodynamic properties of naphthalene which occur in response to compression, showing quantitatively how the intermolecular interactions absorb pressure.
DOI: 10.5286/isis.e.rb1820429
title: Quantum criticality in the Kitaev system alpha-RuCl3

description: The experimental realization of a Kitaev model on the honeycomb lattice has been a major topic in a condensed matter physics because the model uniquely provides exactly solvable quantum spin liquid ground states regarding fractionalized Majorana fermions. The newly discovered alpha-RuCl3 forming a perfect honeycomb lattice with Ising-like spin-spin interaction has strong indications that it lies in proximate to a Kitaev spin liquid phase. Although the material exhibits antiferromagnetic ordering below 6.5 K, the hidden Kitaev physics in the ordered ground state is still ambiguous, and an external magnetic field can give a control parameter for addressing Kitaev Physics. We propose inelastic neutron scattering study on the alpha-RuCl3 single crystal to explore the magnetic field driven quantum phase transition and quantum criticality.
DOI: 10.5286/isis.e.rb1900014
title: Metastable skyrmion lattice phase in Cu2OSeO3

description: Skyrmions are topologically protected, nano-sized objects which have been shown to exist in the spin textures of a range of magnetic materials. As we have recently demonstrated, muSR is a promising method for exploring skyrmion lattice (SL) physics. We recently investigated non-equilibrium SL phases in the Co-Zn-Mn system, but owing to the limited cooling rate available and the disorder inherent in this system, our results were ambiguous. In order to complete this timely project, we propose to use the proven fast-cooling rate available on the ARGUS spectrometer to investigate Cu2OSeO3, which shows both (i) unambiguous evidence for a very large metastable response and (ii) a large response for equilibrium skyrmions in the ISIS time-window. This Rapid Access proposal will enable us to complete this first study of SL metastability before the end of the PI's current post.
DOI: 10.5286/isis.e.rb1620014
title: Novel quantum spin liquid state in the S=3/2 dimer lattice in Ba3ZnRu2O9

description: We have discovered a novel type of quantum spin liquid in a hexagonal lattice of Ru5+ dimers in Ba3ZnRu2O9, where any traces of the Curie tail or glassy behavior have not been detected down to 50 mK. In addition, we have finely controlled the magnetic ground state from an antiferromagnetic order to the gapless spin liquid state by making a solid solution between Zn2+ and Co2+.  We request 3 days on the WISH diffractometer to collect data from the three samples Ba3Co1-xZnxRu2O9 (x=0, 0.2 and 0.4) at temperatures from 4 to 300 K. WISH data are required to observe any magnetic order, and also to study any unusual lattice effects such as the excess [101] microstrain broadening of diffraction peaks at low temperatures associated with spin singlet dimer-formation in the analogue Ba3CaRu2O9 that was revealed from previous WISH data.
DOI: 10.5286/isis.e.rb1620041
title: Crystal and Magnetic Structures of Topochemically Oxidised A-site Ordered Materials

description: The control of physical properties through cation ordering in perovskites often gives rise to unexpected and desirable functionality. Of particular interest in the preparation of cation ordered materials are phases that result from the intergrowth of two different simpler structures. Notably, the structure of Y1.1Ca2.3Ba1.6Fe5O13 can be derived from the intergrowth of YBa2Fe3O8 and Ca2Fe2O5. We have developed this chemistry by synthesising the following three new series of samples;1. Cation and oxygen vacancy ordered Y1+yCa4-x-yBaxFe5O13 phases2. Cation ordered Y1+yCa4-x-yBaxFe5O15 perovskites (by topochemical oxidation of the above materials).3. Cation disordered Y0.2Ca0.8-xBaxFeO3 perovskites (disordered analogues of the above materials)We request 3 days on WISH to record diffraction patterns of 12 samples (4 from each series), each ≈1 g.
DOI: 10.5286/isis.e.rb1710090
title: Dynamics in a new skyrmion spin texture in GaV4S8

description: Topological physics was the subject of this year's Nobel Prize for Physics and over forty years after the groundbreaking work of Kosterlitz, Thouless and Haldane, remains an exciting and growing research area with the subject of skyrmions arguably its hottest topic. Skyrmions are topological objects which have been shown to exist in the spin textures of a range of magnetic materials. As we have recently demonstrated in our muSR work on these systems that muSR is a promising method for exploring the static and dynamics physics of skyrmion lattices. Here we propose to exploit the strengths of ISIS muons to measure the dynamics associated with the skyrmion phase of GaV4S8 which has recently been proposed as a new class of skyrmionic material that hosts a unique form of skyrmion spin texture.
DOI: 10.5286/isis.e.rb1710111
title: Humic acid interactions with alumina surface and the effect of perfluoroalkyl substances

description: In the soil environment, organic matter such as humic acid has a strong influence on the behaviour of organic pollutants such as perfluoroalkyl substances (PFASs) and their interactions with other soil constituents such as mineral surfaces. As it is common that mineral surfaces in soils have a coating of organic material, the behaviour of this type of system and its role for sorption of organic contaminants warrants further investigation. Humic acids are one of the main components of organic matter found in soils. In the proposed neutron experiment, we aim to study the behaviour of humic acid at an alumina (Al2O3)/water interface, and investigate how PFASs sorb onto this model soil system.
DOI: 10.5286/isis.e.rb1710159
title: Pickering emulsions stabilized with oxidised cellulose nanofibrils and starch

description: Our group has been working functionalised cellulose nanofibrils which form gels in aqueous formulations. Previously we have used these fibrils to stabilise oil-in-water pickering emulsions, and SANS & rheology show that these emulsions are stabilized by added salt when anionic celullose fibrils are used but not when using cationic fibrils. Addition of  soluble starch polymers creates a gel in the continuous aqueous phase which helps to prevent creaming in these suspensions. Addition of surfactant assists in lower energy emulsification. Therefore here we would like to determine the structural effect of adding salt and surfactants to these starch/cellulose emulsions by studying the structures at the droplet/water interface. Selective deuteration will enable us to highlight the cellulose walls, any penetration of the starch into the walls and the location of surfactant within them.
DOI: 10.5286/isis.e.rb1710167
title: PROBING DRUG PHARMACODYNAMICS BY QENS: THE EFFECT OF CISPLATIN-LIKE ANTICANCER DRUGS ON DNA DYNAMICAL PROFILE

description: Water supports vital biochemical processes in living organisms, namely through maintenance of the three-dimensional architecture of biopolymers by a tight interplay with their hydration shells. Hence, any mobility changes within this hydration layer may affect the biopolymer´s conformational and dynamical profile, which rule biofunctionality.Building on the success of a previous experiment on human cells (RB1510054, paper under review [1,2]), the present study aims to apply QENS (with isotope labelling) for probing the effect of cisplatin-like anticancer drugs on the dynamical behaviour of DNA, through the impact on its hydration layer. This is a timely and innovative way of tackling a drug´s pharmacodynamics at a molecular level, that should provide data allowing a thorough understanding of the drug´s mode of action, water being suggested as a secondary pharmacological target.
DOI: 10.5286/isis.e.rb1710209
title: Magnetic ordering in CaFe3O5 and CaFe5O7

description: This proposal is to explore the evolution of magnetic ordering in two members of the homologous series CaFe2O4(FeO)n with n = 1, & 3, and to correlation the behaviour of the magnetism with crystal structures and the possibility of charge ordering. This is a topical area related to the current interest in magnetite and related compounds.
DOI: 10.5286/isis.e.rb1710414
title: In-Situ Studies of Electrochemically Enhanced Performance in Perovskite Electrodes for Solid Oxide Cells

description: Recent studies in our laboratory have shown that a range of A-site deficient perovskite oxides, with carefully tuned chemical compositions, exhibit excellent properties when used in devices such as solid oxide fuel cells.  The key to this performance is the migration of cations from the bulk single phase material, forming a catalytically active secondary phase, under reducing conditions in an exsolution process. Recent work in our laboratories has shown that the exsolution may also be induced by electrochemical poling, which has enhanced performances even further.  The aim of this work is to study the electrochemically induced exsolution in-situ and compare it with conventional exsolution under reducing conditions, whilst also probing the crystal structure of these A-site deficient perovskites.
DOI: 10.5286/isis.e.rb1710483
title: More than the sum - oxidation behaviour of mixed fatty acid monolayers

description: Single molecule thin films of various surface-active species are found on the surface of water bodies from the sea down to microscopic spray droplets. These films affect the properties of the water droplet and of the substance that makes up the film and have significant effects on atmospheric chemistry, meteorology, and, ultimately, climate change. Our work looks at films composed of mixtures of substances (e.g. oleic and stearic acid) and compares their behaviour to that of pure films. This experiment will study changes in orientation and phase behaviour of various relatively unreactive substances at the surface when a reactive substance present as part of a mixed film undergoes oxidation. NR is excellent for studying such systems, and we combine it with an innovative infra-red reflection system in order to study the phase behaviour of these mixed systems during oxidation in real time.
DOI: 10.5286/isis.e.rb1720068
title: Incipient magnetic frustration in a metal organic-framework with windmill lattice.

description: The aim of the proposed experiment is to use single-crystal neutron magnetic scattering experiments to study spin correlations in the correlated paramagnet regime of a chiral metal-organic framework (MOF). Magnetic exchange pathways in the compound NaMn(HCOO)3 adopt the trillium hyperkagome structure, which is known to support a chiral frustrated magnetic state. The key objectives of this proposal are (i) the determination of spin correlations within the strongly-correlated paramagnetic regime in order to characterise the magnetic frustration; and (ii) to understand the influence of aligned magnetic fields on this paramagnetic spin texture. Our results will shed light on the materials magnetocaloric behaviour, and provide the first experimental study of spin correlations on this chiral hyperkagome net.
DOI: 10.5286/isis.e.rb1720083
title: Cellulose-based polyelectrolytes for microencapsulation: conformational transitions triggered by multivalent salts

description: Addition of multivalent salts to water soluble polyelectrolytes, such as sodium carboxymethyl cellulose (NaCMC), induces conformational change to the polyelectrolyte structure, resulting in aggregation and precipitation, or gel formation, with increasing salt concentration. We have demonstrated that this transition can be exploited with NaCMC for encapsulation, specifically with microfluidic techniques. Whilst the phenomena has been previously reported, the complex effects of salt addition on polyelectrolyte conformation (charge screening, ion bridging and charge inversion) have not been fundamentally answered. We aim to address the equilibrium state of polyelectrolyte-salt mixtures, and mechanistic understanding of the conformational transition, to enable us to precisely design a (non-equilibrium) framework for directional solidification of these materials for encapsulation.
DOI: 10.5286/isis.e.rb1768044
title: SANS evaluation of novel nanocolloidal drug carriers

description: With the beamtime requested we plan to employ small-angle neutron scattering (SANS) to study novel nanocolloidal drug carriers prepared using lipids, surfactants and co-surfactants. These can address solubility, stability and bioavailability issues of drugs.  SANS will be used to monitor: Size/thickness of surfactant layer of developed systems. Orientation/ spatial arrangement of components viz. surfactant, co-surfactant and surfactant supporting agents around the lipid core or in the vesicles. Existence of other structures viz. micelles, supercooled melts or nanostructured lipid carriers. Particle aggregation. Particle-particle interactions. Mesophase or smectic nature of the systems.Systems are aqueous nanodispersions and D2O will be used for neutron contrast. 25 & 37 ◦C, will be used to study changes and amorphous/crystalline nature.