cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1820289
title: Taking skyrmions for a spin

description: Magnetic skyrmions have a robust topological magnetic structure, which makes them ideal for use as binary information carriers. The skyrmions appear in a well-ordered lattice state in cubic B20 helimagnets, which can be collectively manipulated by electric currents, thermal, and magnetic gradients. Recently, we have shown that skyrmion lattices in Cu2OSeO3 rotate in radial magnetic field gradients. Here, we propose a systematic study of the response of the skyrmion lattice in MnSi to radial thermal gradients, again expecting a circular motion of the lattice.
DOI: 10.5286/isis.e.rb1910299
title: High-resolution phonon spectra of silicon nitride phases

description: Silicon nitride is a mechanically tough and light-weight ceramic material able to withstand high temperatures. It is therefore becoming increasingly attractive for use in specific technical applications. The material exists in two distinct phases under normal conditions, alpha and beta, which are both stable. The alpha phase may only be transformed into the beta phase under specific conditions, which involve a combination of high temperature, high pressure and/or significant inclusion of impurities. The reverse process (beta to alpha) has never been observed. In order to understand this behaviour we propose to model the material based on DFT calculations. In order for the model to be accurate, the basic vibrational motions of atoms (phonons) need to properly included. Inelastic netutron measurements would provide an experimental benchmark to assess the quality of the models.
DOI: 10.5286/isis.e.rb1910330
title: Martensite detwinning mechanisms of aged Co-Ni-Ga shape memory alloys

description: Pseudoelastic CoNiGa high-temperature shape memory alloys (HT-SMAs) show a wide range of transformation temperatures and lower processing costs than conventional Ni-Ti-X HT-SMAs which renders them useful for high temperature applications in automotive industries. Recent studies demonstrated stable functional properties from ambient temperature up to 200°C. In addition, heat treatments at intermediate temperatures promote the precipitation of γ´- particles which significantly increases the hardness of the austenite matrix. In particular the γ´ - particle morphology varies with ageing conditions and leads to functional properties which differ from the particle free material. In-situ mechanical tests at elevated temperatures are conducted using the SXD Laue Diffractometer  to assess the detwinning mechanism and martensite twin domain relationships in depth.
DOI: 10.5286/isis.e.rb1910388
title: Zr-based metal-organic frameworks as carbon-free energy carriers: a study of their structural interactions with ammonia

description: Structural information of Zr-based MOFs including UiO-67, m-UiO-67, and UiO-bpydc upon ammonia loading will be investigated by an in situ neutron powder diffraction technique. Rietveld refinement will be conducted to elucidate adsorption geometries and locations of ammonia in this MOF-guest system, enabling an understanding of the exceptional ammonia uptake and the unusual adsorption behaviours of m-UiO-67 and UiO-bpydc. This work will lead to an improved ammonia storage and a more rational design for catalytic ammonia decomposition.
DOI: 10.5286/isis.e.rb1910468
title: Defect structure of oxygen-deficient Yb2Zr2O6.5

description: Ytterbium zirconate is of fundamental interest as a model frustrated magnet, and of potential technological importance as a thermal barrier material. In both cases oxygen vacancies are known to play a central role in determining physical properties. We have grown a large single crystal of oxygen- deficient Yb2Zr2O6.5 and we propose to determine its defect structure using diffuse neutron scattering on SXD. The sample adopts the fluorite structure and this opens up the possibility to study magnetic frustration on the FCC lattice. Furthermore the thermal conductivity is known to be anomalously low compared to predictions for random, isolated oxygen vacancies. We shall determine the nature of the oxygen defects in order to assess their role in suppressing the thermal conductivity, and the migration of oxygen at elevated operating temperatures.
DOI: 10.5286/isis.e.rb1910598
title: Probing the ground state magnetic structure of single crystalline Lu3Fe5O12 and Yb3Fe5O12

description: Lu and Yb counterparts of RE3Fe5O12 will be appropriate platform to reveal the complex magnetic ground state of rare earth iron garnets with common formula RE3Fe5O12. Lu3+ does not possess magnetic moment due to the absence of unpaired electrons with 4f14 electronic configuration, but Yb3+ possesses finite magnetic moment for having 4f13 ground state configuration. Hence, studying these two compounds together will explore the role of rare-earth moment in the magnetic ground state of these garnets. No definitive work on single crystal neutron diffraction study on these compounds has been performed so far. Hence, detailed study on magnetic ground states of these garnets is owed to plant to get insight into the fundamental physics and single crystal neutron diffraction is the best way to explicitly solve the magnetic structure of these compounds.
DOI: 10.5286/isis.e.rb1910610
title: Exchange Spring Evolution in SmCo5/Fe and NdCo5/Fe

description: We propose to investigate the evolution of the exchange spring (ES) in NdCo5/Fe and SmCo5/Fe with temperature and magnetic fields using polarized neutron reflectometry. The exchange coupling at the interface leads to an ES formed in the soft-magnetic Fe layer when an external field is applied opposite to the initial saturation or at along a hard axis of the material. In NdCo5, a spin-reorientation transition just below room temperature leads to a change of the easy axis from the c-axis to the a-axis. This allows to tune the ES without changing the field or sample orientation. In particular, we will use OFFSPEC to gain deeper insight into off-specular asymmetric spin-flip scattering observed in fields &gt; 0.1 T. The scattering is highly asymmetric due to the Zeeman effect and may indicate a domain formation. However, the origin and field dependence is not clearly understood as a domain form
DOI: 10.5286/isis.e.rb1520019
title: INS Studies of Porous Metal-Organic Framework Materials for Ammonia Storage

description: The development of new porous MOFs is receiving considerable attention worldwide owing to their potential for gas storage, separation, and purification. We seek to develop a highly novel ammonia storage system and request 11 days on TOSCA to study the binding interaction between adsorbed ammonia molecules (NH3) and two functional porous MOF materials [NOTT-300(Al) and NOTT-300(V)] as a function of NH3 loading. This proposed study will investigate the vibrational properties exhibited by both adsorbed gas substrates and the porous hosts. These two MOFs exhibit surprisingly high storage capacity for ammonia at ambient conditions (15.2 mmol/g), suggesting the presence of specific guest-host interaction with the respect to the functional groups on the pore surface. The proposed study aims to reveal the nature of the ammonia uptakes by analysing their vibrational/rotational spectra.
DOI: 10.5286/isis.e.rb1520083
title: Probing hybridization strength and homogeneity of valence mixing in magnetically-ordered, intermediate-valence EuCu2(SixGe1-x)2.

description: The compounds we want to study belong to the well-known tetragonal RM2X2 family (R: rare earth, M: d element, X: Ge, Si). In EuCu2(SixGe1-x)2, the Eu valence changes, as a function of the Si concentration x, from close to 2+ (magnetic, 4f7) for x = 0 to strongly intermediate, nonmagnetic above xc = 0.65. In the vicinity of xc, the system exhibits Kondo effect and heavy-fermion properties, which are quite unusual for Eu. We propose to probe the sd-f hybridization in these materials by studying its effects on the crystal-field scheme of Er impurities, which can sense the delocalization of 4f electrons. Another goal is to check the absence of ionic Eu3+ excitations in Ge-rich compounds despite the sizable deviation from the 2+ valence. The measurements can be done on MARI with sufficiently thin samples and using a low enough Er concentration so as not to affect the properties of the host.
DOI: 10.5286/isis.e.rb1520186
title: Investigating trends in lithium diffusion in doped LiFePO4 materials

description: There is widespread interest in the development of lithium-ion batteries (LIBs) for rechargeable applications, as they currently offer the highest energy density (amount of charge stored per gram) of all commercial rechargeable batteries. LiFePO4 is an increasingly important battery cathode material, and is already in use in some portable devices, although there is ongoing research to further improve its performance at high discharge rates. We have synthesised LiFePO4 using a continuous process, which is capable of producing nanomaterials on a kg/h scale. We have also made V- and Nb- doped variants which show improved electrochemical performance.   µSR would allow us to compare the Li diffusion in our mass-produced material compared to smaller-scale syntheses in literature. We also expect to see enhanced Li diffusion in our doped samples.
DOI: 10.5286/isis.e.rb1520206
title: muSR study of a relaxor ferromagnet

description: As a consequence of cation disorder, the compound La3Ni2SbO9 behaves as a new type of magnetic material, a "relaxor ferromagnet", somewhat analogous to a relaxor ferroelectric, with magnetic domains too small to be detected by neutron diffraction forming below 105 K. This formation of domains was ascribed to the presence of local antimony-rich regions wherein the magnetic coupling between Ni2+ cations is disrupted, thus creating a domain wall. A compound with these properties would usually be classified as a cluster glass, but the origin of the behavior in this case, in a crystalline material with a cation distribution that is ordered in one sense but disordered in another, is quite different. We propose a comprehensive study of this new material using muSR to study local order and dynamics, extending the frequency range of fluctuations already probed using ac susceptibility.
DOI: 10.5286/isis.e.rb1520340
title: Entangled superconductivity and magnetic and charge density waves in A1-xA'xFe2-yByAs2

description: We aim to study select samples of hole and electron doped (A,A')(Fe,B)2As2 (A=Ba, Sr, or Ca; A'=Na, K and B=Co, Ni, or Pt) iron pnictides. These materials exhibit robust in-plane spin density waves (SDW) that compete with superconductivity (SC) in a narrow region of the phase diagram.  In SrFe2-xPtxAs2, charge density waves have also been reported. In a recent discovery achieved using WISH and HRPD, we identified a new out-of-plane magnetic SDW state, C4, just before SC was about to be induced. This phase persists at temperatures up to ~70 K as a function of A/A'.  The universality of C4 in all the investigated hole doped systems coupled with distinct differences makes it clear that internal chemical pressures and the nature of doping play major roles that need to be determined. 2D determinations of the C4 phase and the nature of SC/SDW/CDW state coexistence are the goals of this study.
DOI: 10.5286/isis.e.rb1520348
title: Local Field fluctuations and Mu Dynamics in Vanadium Dioxide Compounds

description: This is an in depth study of magnetic fluctuations and local field dynamics leading into the low temperature magnetic phase of Vanadium Oxide compounds (VO2, VO2:W and VO2:Ti) via ZF- and LF-MuSR. Additionally, we propose ZF-MuSR measurements to characterize local Mu (OMu-, c.f. OH-) dynamics occurring in the higher temperature (T&gt;300K) metallic phase. This is a direct follow up to RB1320350 and RB1410438, where the main goals were to provide an initial survey of the muon (muonium) states and motional characteristics in VO2 compounds and then to specifically study the low temperature region where we have found a magnetic phase. These newly proposed measurements will provide information relating to the magnetic precursors and local Mu motion in the non-magnetic phase. These studies will yield insight into the various transitions and potentially the roles impurities play in modifying each.
DOI: 10.5286/isis.e.rb1520403
title: High precision measurement of the spin waves in Yttrium Iron Garnet

description: Yttrium Iron Garnet (YIG) is a material with extremely wide ranging applications. It is a ferrimagnetic spinel with the narrowest ferromagnetic resonance linewidth of any known material. Despite decades of experiments on this material, data relating to its full magnon spectrum is sparse. The spectrum is known to contain 20 branches, but the most thorough work to date relies upon a 3-parameter hamiltonian derived from fitting just 3 (the only 3 that were observed in what is still the only INS measurement on this material). Increasing interest in YIG for applications in magnonics (the magnon equivalent of electronics) necessitates a direct measurement of the optical magnon modes, which are crucial for understanding and exploiting this material. We propose to take advantage of large single crystals that are commercially available and thoroughly map the entire excitation spectrum.
DOI: 10.5286/isis.e.rb1520442
title: Study of Pressure Induced Ferromagnetic to Antiferromagnetic Phase Transition in the 2-dimensional Kondo Lattice CeRuPO

description: Ce-based Kondo lattice systems present exotic behavior due to the competing RKKY, Kondo and crystal field interactions. The Kondo lattice CeRuPO, crystallizing in the famous ZrCuSiAs-type structure, is one of such compounds which presents interesting magnetic properties and strong correlation effects. At ambient pressure, CeRuPO is found to undergo a ferromagnetic transition at TC = 15 K.  External pressure is found to change the magnetic ground state from a ferromagnetic to an antiferromagnetic state at a pressure of about 0.87 GPa. The magnetic ordering is completely suppressed at about 3 GPa. Detailed investigations of the antiferromagnetic ground state under pressure using neutron diffraction will be necessary to determine the magnetic structure. We therefore propose to carry out powder neutron diffraction measurements on CeRuPO under pressure using the WISH diffractometer.
DOI: 10.5286/isis.e.rb1520463
title: Magnetic Order in the Pyrochlore Phase of Gd2Zr2O7

description: Along with the titanate and stannate materials, Gadolinium Zirconate, Gd2Zr2O7, makes up a series of model pyrochlore systems characterized by a Heisenberg antiferromagnetic coupling with dipole-dipole interactions as the leading perturbation. There is evidence for a magnetic transition in Gd2Zr2O7 at 0.7 K although both how this ordering develops and the nature of the magnetic ground state of Gd2Zr2O7 are unknown. We propose to use muon spectroscopy to investigate the evolution of the magnetic order in pyrochlore Gd2Zr2O7 down to low temperature.
DOI: 10.5286/isis.e.rb1820276
title: Dynamics of Self-Assembled Perfluoroalkyl Block Copolymers in Solutions Using Small-Angle Neutron Scattering

description: Block copolymers are composed of two or more chemically different polymer chains covalently linked together, and are capable of forming self-assembled nanoparticles in a selective solvent. We invented block copolymers containing perfluoroalkyl block which can form nanoparticles in solutions and further can be used as superhydrophobic coating materials. Using small-angle neutron scattering beamline at ISIS, we aim to measure the dynamics of block copolymers in such self-assembled solutions. We expect to understand the relation between the dynamics and the resultant nanoparticle structures. This knowledge will make us to control sizes and shapes of the nanoparticles and enhance the superhydrophobic surface properties fabricated from the nanoparticles.
DOI: 10.5286/isis.e.rb1820471
title: Porosity Analysis in Suspension Thermal Sprayed YSZ Coatings using Spin-Echo Small-Angle Neutron Scattering (SESANS)

description: Suspension thermal spraying (STS) techniques enable the use of sub-micron powder particles as feedstock, as opposed to the traditional use of dry powders with micrometric size, leading to nano-structured coatings. Yttria-stabilised zirconia (YSZ) is a widely used thermal barrier coating in aeroengines and suspension sprayed YSZ has been reported to present lower thermal conductivity, enhanced phase stability and strain tolerance. The effect of processing parameters on the microstructure, especially porosity, is largely overlooked in the literature despite its central effect on performance. The objective of this proposal is to understand the evolution of porosity on YSZ coatings deposited via STS on as-received conditions and after heat treatment at 1100, 1200, 1300 and 1400°C, studying the sintering of nanopores into micro-features due to the capability of SESANS to measure up to 20 um.
DOI: 10.5286/isis.e.rb1869015
title: Helimagnetic correlations in FeCl3

description: The recent discovery of skyrmions and skyrmion lattices in materials with no inversion symmetry and their corresponding potential applications of Skyrmions in magnetic information storage and processing devices has increased the scientific interest in these chiral materials. The archetype chiral system is MnSi, on which various studies have been performed. The question remains what the influence is of applying chemical pressure in the form of Iron doping in MnSi. Earlier measurements show the existence of two QCP in Mn1-xFexSi. However, it remains unclear what exactly happens to the phase diagram under field, the (chiral) magnetic correlations and fluctuations present in MnSi if chemical doping is introduced as well as to the crystaline effects and relaxations observed for MnSi. To answer these questions, we propose to study Mn1-xFexSi with x = 0, 0.08 and 0.10 with SANS on LARMOR.
DOI: 10.5286/isis.e.rb1910069
title: Neutron reflection studies on model wax films reconstituted from chemicals

description: Morphological features of plant waxes vary from species to species, but little is understood about what controls these morphological changes although it is widely believed that wax morphological structures directly implicate their functional roles in protecting the plants by mediating water and nutrient transport and preventing bacterial and fungal attacks etc. However, native wheat waxes bear large topical waxy crystals whilst those of sugar beet are rather smooth. We hypothesise that these morphological features are controlled by wax composition. Our AFM imaging has confirmed the transformation with alcohol composition. The structural information from NR is unique and will provide the whole structural features across wax films. We request 4 days of Offspec/ProRef time for completing this experiment.
DOI: 10.5286/isis.e.rb1910265
title: Lipid exchange in circularized nanodiscs

description: Nanodiscs (NDs) are discoidal lipid-protein aggregates composed by a lipid bilayer surrounded by a protein belt. NDs are suitable systems to investigate membrane protein structure in solution by scattering (e.g. SANS and SAXS), spectroscopy (e.g. NMR) and Cryo-EM techniques. Recently, we developed three types of protein belts (named csE3, cs1D1 and csDH5), aiming at improving ND thermal and time stability for membrane protein structure characterization in solution. Here we propose to complement the structural characterization of csE3, cs1D1 and csDH5 NDs by investigating lipid-exchange between NDs emerged as a key dynamic aspect to determine the ND capability to mimic lipid membranes.
DOI: 10.5286/isis.e.rb1910284
title: Investigating structural organization of hyaluronic acid-based nanogels encapsulating antimicrobial drugs

description: We want to characterize the physico-chemical properties of self-assembling nanogels composed of octenyl-succinic anhydride modified hyaluronic acid and lipophilic antibiotics or antimicrobial peptides. We have assessed the efficacy of antimicrobial drugs in OSA-HA nanogels in vitro and in vivo, but we still lack basic understanding of the structure of nanogels upon drug loading and the effect of this structure on the formulation efficacy. We want to assess the structural organization of the nanogels over time, the spatial distribution of the drug within the gel and the release mechanism from the gel. Additionally, we would like to look into the behaviour of nanogels in blood plasma and structural stability after freeze drying and reconsitution. By obtaining such insight on structural organization, we will be able to better interpret results of efficacy studies and optimize the nanogels.
DOI: 10.5286/isis.e.rb1910434
title: Investigating the spectral signature of confined hydrogen in vanadium metal hydride thin-films

description: Hydrogen is one of the major candidates to replace carbon-based fuels with sustainable energy sources. One of the major challenge is hydrogen storage and transport, limited by the low density of gaseous hydrogen. An attractive solution involves metal hydrides, which shows both high volumetric density and favourable thermodynamic properties regarding the uptake and release of hydrogen. Said properties can be tuned by, for instance, strain or finite size effects, and considerable efforts are directed toward nano-sizing metal hydrides. In this context, we are interested in investigating the hydrogen dynamics, through its vibrational spectra, in both confined and bulk-like vanadium hydride VHx thin-films. The results will provide insights on the geometry and occupation of the hydrogen sites, which is critical to understand the hydrogen mobility in confined metal hydrides.
DOI: 10.5286/isis.e.rb1910440
title: Self-assembling antimicrobial peptides: interactions with model lipid membranes

description: We propose to investigate antimicrobial peptides that self-assemble into well-defined nanostructures. Previous SAXS results have shown that the peptides form rather robust platelets/fibers (nanosheets) with well-defined dimension of about 100x6x3 nm3 which persist with the attachment of poly(ethylene glycol) (PEGylation). Recent investigations have shown that the peptides that form nanosheets exhibit low cytotoxicity but significant antimicrobial action, while unstructured peptides were significantly more toxic and also prone to enzymatic degradation. In order to understand the biological behaviour, the basic physico-chemical characterizations are needed, in particular at surfaces that might provide insight to their cell interactions.
DOI: 10.5286/isis.e.rb1910542
title: Structures of cardiolipin-bound cytochrome c in pathological conditions

description: Cardiolipin (CL) is a structurally unique dimeric phospholipid localized in the inner mitochondrial membrane, which is known to provide essential structural and functional support to proteins involved in mitochondrial bioenergetics. The interaction between CL and cytochrome c (Cytc) regulates the binding states of Cytc to the membrane and, therefore, directly affect the electron transport function of Cytc in mitochondrial respiration. A loss of CL content, alterations in its acyl chain composition have been associated with mitochondrial dysfunction leading to bioenergetic diseases, including Alzheimer, heart failure, and aging. This proposal aims to resolve the structures of CL-bound Cytc utilizing remodeled CL to mimics pathological conditions, in comparison with the obtained structures for the healthy states.