cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5517/ccdc.csd.cc21f90t
title: CCDC 1889605: Experimental Crystal Structure Determination

description: Related Article: Yichen Wang, Yuzhen Chen, Xiaoping Li, Yukang Mao, Weiwen Chen, Ruoting Zhan, Huicai Huang|2019|Org.Biomol.Chem.|17|3945|doi:10.1039/C9OB00419J
description: An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
DOI: 10.5286/isis.e.rb1510004
title: What is the Room Temperature Structure of NaTaO3?

description: The current proposal seeks to establish the origin of t non-perovskite-like peak splitting observed in HRPD data for NaTaO3.  It is our hypothesis that this is a result of the co-existence of two orthorhombic( Pnma & Cmcm ) phases at room temperature.  This postulated to be consequence of a kinetic barrier to the re-arrangement of the tilts associated with the Pnma ¿ Cmcm transition. To test this hypothesis four samples of NaTaO3 prepared using different thermal annealing protocols will be studied, including some variable temperature measurements.
DOI: 10.5286/isis.e.rb1510176
title: Phonon dispersion and defects in pyrochlores

description: Pyrochlores exhibit a rich variety of exotic physical properties including fractionalization, topological order and emergent magnetic monopoles in the classical spin ices, and a Higgs transition to a ferromagnetic phase for their quantum analogues. The magnetic ground states of these systems are strongly sample dependent, suggesting a key role for defects. Understanding the phonons allows us to predict stable defect structures and model the strain-field relaxation around defects. The absence of a complex magnetic ground state in yttrium titanate greatly simplifies density-functional calculations, and here we propose to test our lattice dynamics model using inelastic neutron scattering.
DOI: 10.5286/isis.e.rb1510293
title: In Situ Structural Studies of Low Temperature Synthesised TiP2O7 and V-Doped TiP2O7

description: The AX2O7 series has garnered much recent attention due to its ability to host a wide range of 4+ cations.  The members of this series have been shown to exhibit complex structures (including super-structures), and some members show negative thermal expansion at elevated temperatures, including ZrV2-xPxO7.  TiP2O7 itself adopts a 3x3x3 cubic superstructure at room temperature, and displays positive thermal expansion upon heating.  When synthesised at a low temperature, and also with the addition of V metal, there is no evidence of superstructure in either pattern.  Both exhibit an irreversible phase transition upon heating to the apparent ideal cubic structure. This proposal is aimed to investigate the structures of low temperature synthesised TiP2O7 and its vanadium-doped analogue, and to investigate the unusual structural transition from pseudo-cubic to apparent cubic upon heating.
DOI: 10.5286/isis.e.rb1510327
title: Determination of the Crystallographic and Magnetic structures of RbMnBr3, RbFeBr3 and RbNiBr3.

description: We propose to study the crystal structures of RbMnBr3, RbFeBr3 and RbNiBr3 between 300 and 0.3 K. RbMnBr3 under goes two structural phase transition by reducing Rb coordination. In this process the linear chains of BX3- octahedral shift along the c-axis. The resulting  unit cell is aV3 enlarged in the basal plane. Finally the accompanied disorder in the structure is gone in the lowest temperature phase. which enlarges by a factor 4a.For RbFeBr3, one expect on the basis of dielectric measurement to observe a similar sequence. This has so far not been observed . For RbNiBr3 no low temperature data are available. The structural phase transition have a distinct effect on the magnetic ordering going from incommensurate ordering volume on SXD we will be able to determine the crystal and magnetic ordering in detail.
DOI: 10.5286/isis.e.rb1510377
title: Measuring hydrogen gradients in amorphous silicon thin films for photovoltaic applications

description: This experiment addresses the role of hydrogen in determining both quality and stability of surface passivation materials for silicon solar cells. Surface recombination causes losses in such solar cells, but can be reduced by depositing passivating surface films of amorphous hydrogenated silicon (a-Si:H). Long term stability and thermal stability is however a challenge due to hydrogen desorption. It is not easy to measure hydrogen concentration gradients in thin films using other experimental methods than neutron reflectometry. Our samples are precharacterized with X-ray reflectometry and photoconductance minority carrier lifetime measurements. We ask to measure 10 a-Si:H/Si bilayers and expect the measuring time based on earlier experiments at ILL to be approximately 12 hours, including setup time and alignment. Thus we ask for 10 x 12 = 120 hours of beam time, or 5 days.
DOI: 10.5286/isis.e.rb1510481
title: Magnetic excitation in Sr2IrO4 : Establishing links to Cuprate superconductors

description: The strontium iridate Sr2IrO4 has recently received a special attention because of its closeresemblance to undoped high-Tc cuprate in terms of structural, electronic, and magnetic aspects.We have recently measured magnon dispersion using the resonant inelastic x-ray scattering(RIXS) technique. A dispersive magnon branch with a bandwidth of ~200 meV has beenobserved. However, due to insufficient energy resolution of the state-of-the-art RIXS instruments,the magnon gaps, of quantum and classical origins, have not been quantified. The proposed INSmeasurements are aimed (i) to quantitatively measure the magnon gap at the zone center andzone boundary, and (ii) to investigate the origin of the new high energy magnetic excitationsobserved in the RIXS. We propose to measure the magnetic excitation up to the energy transfer of~ 600 meV using the TOF Merlin spectrometer.
DOI: 10.5286/isis.e.rb1510510
title: Crystal structure and phase transitions of Sr2IrO4

description: Sr2IrO4 is an important material in the field of condensed matter physics, being a proposed J_eff=1/2 Mott insulator. Recent publications have shown that the reported low- and room-temperature space group (I4_1/acd) cannot be correct due to the presence of forbidden reflections over a wide temperature range. Small distortions can have dramatic effects on the electronic structure of iridate materials. The Ir-O orbital overlap is directly affected by IrO6 octahedral tilts and rotations. Therefore, the determination of the correct structure is essential for future theoretical and experimental investigations of this important system. The first objective of this experiment is to determine the correct space group for Sr2IrO4. The second is to investigate the (so far unexplored) high temperature phase transitions of this compound to understand the origin of the distortion at room temperature.
DOI: 10.5286/isis.e.rb1510543
title: Neutron-induced soft errors in Flash Memories with feature size down to 16 nm

description: Flash memories are the electronic component in which the feature size is scaled more rapidly and which have the largest capacity among semiconductor devices. We plan to expose different Flash memories at ISIS, to study the response of these devices to the neutron beam provided by the ChipIR line, which reproduces the terrestrial neutrons spectrum with several orders of magnitude of acceleration. Samples with both NAND (with a feature size down to 16-nm) and NOR (down to 45 nm) architecture will be exposed to neutrons and results will be compared with those previously obtained at VESUVIO. Some of these samples will also be irradiated at the Los Alamos Neutron Science Center (LANSCE) to compare the effect of different energy spectra on the soft error rate. The analysis will be focused on Floating Gate (FG) errors and variability (lot-to-lot, sample-to sample, cell-to-cell etc.).
DOI: 10.5286/isis.e.rb1520391
title: Magnetic structure in the one-third magnetization plateau phase of a triangular quantum magnet

description: We propose single crystal diffraction measurements to probe the magnetic structure in the 1/3rd magnetization plateau phase observed for fields in the range 10-15 T in the triangular quantum (S=1/2) antiferromagnet Ba3CoSb2O9. Magnetization plateau phases are conceptually very interesting as their stability (why magnetization is constant in a varying applied magnetic field) cannot be understood at a mean-field level, collective zero-point quantum fluctuations are required to stabilize such phases. We plan to experimentally test theoretical proposals that the magnetic structure has collinear up-up-down order polarized along the field with a strong ordered moment reduction. Those studies are complementary to our inelastic neutron scattering studies of crystal field transitions and quantum effects in the low-energy spin dynamics.
DOI: 10.5286/isis.e.rb1540000
title: NTC2015
DOI: 10.5286/isis.e.rb1540001
title: NTC2015
DOI: 10.5286/isis.e.rb1610007
title: Violation of the Gaussian approximation in the incoherent spectrum of hydrogen-neon liquid mixtures

description: A well-known approach to the self-dynamics of liquids is based on the Gaussian approximation, where it is assumed that the motion of a molecule is fully determined by a unique function of time directly related to the velocity auto-correlation function. Experimental inquiries into the presence of non-Gaussian dynamics are still scarce, particularly concerning low-temperature liquids exhibiting moderate quantum effects (i.e. H2, D2, and Ne). Though experimental evidences of the breakdown of the Gaussian approximation in liquid para-H2 (and in its isotopic mixtures with D2) have been recently obtained by the present authors, the density behavior of this phenomenon and its link with the self-diffusion coefficient are not completely understood. These two issues will be tackled by a new neutron investigation on three liquid para-H2/Ne mixtures exhibiting various hydrogen concentrations.
DOI: 10.5286/isis.e.rb1610037
title: Low temperature phase transitions in ferroelectric tris-sarcosine calcium chloride (TSCC)

description: Small-molecule based ferroelectrics offer several advantages over the currently used materials based on heavy metal oxides (i.e. cost, environmental-friendliness). There are relatively few well-characterised examples of molecular ferroelectrics, in part since the relevant crystallographic studies have relied on X-ray diffraction. Neutron diffraction is the key technique in understanding the behaviour of H-atoms in molecular crystals. Here, we propose to study a  well-known but still poorly understood 'model' molecular ferroelectric, TSCC, based on an amino-acid-salt complex. TSCC is proposed to have four phases as a function of temperature, with transitions at 130, 64 and 42 K. The two highest T phases have been characterised structurally, but only by XRD. Information on the behaviour of H-atoms is essential. The lower two phases have not yet been studied at all, crystallographically.
DOI: 10.5286/isis.e.rb1610303
title: Origin of giant ferroelectricity in perovskite-type Mn2O3

description: Perovskite-type compounds can be both very simple and tremendously complex. Remarkably, even binary perovskite-type compounds may exhibit high level of complexity that leads to intriguing physical behavior. Recently, we discovered that Mn2O3 is non-perovskite at ambient pressure transforms into a perovskite-type structure around 20 GPa and 1200 K. This perovskite-type polymorph can be quenched to ambient conditions. It reveals several magnetic transitions and giant magnetically-driven ferroelectricity, with ferroelectric polarization ranging among the highest values observed in systems of this kind. We will use neutron diffraction on WISH to resolve magnetic structures as well as details of the crystal structure of perovskite-type Mn2O3. This experiment will help us to elucidate the origin of giant magnetically-driven ferroelectricity.
DOI: 10.5286/isis.e.rb1610317
title: Polymer-phospholipid nanodiscs: Modification of polymer hydrophilicity.

description: Polymer stabilized lipid nanodiscs offer enormous potential as tools for enabling membrane protein structural studies & biophysics. Previously we studied nanodisc formation using a poly(styrene-alt-maleic acid) copolymer, and also with a commercially available poly(styrene-alt-maleimide) (PSMI). We now wish to study the polymer chemistry in more detail to investigate the effect of structural changes to help determine how the disc structure is stabilized. We have used RAFT polymerisation to prepare well defined poly(styrene-alt-maleic acid) polymers with a diblock or triblock structure and also where the styrene has been partially sulfonated or instead incorporating acrylic rather than maleic acid. These variations in the hydrophilicity of the polymer alter the aggregate size in preliminary DLS studies but contrast variation SANS is needed to determine the structures formed with lipids.
DOI: 10.5286/isis.e.rb1610329
title: Correlation between structure and properties in Bi0.7La0.3FeO3

description: Bi0.7La0.3FeO3 has received extensive attention in the past years, since this compound exhibits simultaneously ferroelectricity and ferromagnetism at room temperature. Despite the research undertaken in this compound, a number of questions including:  the understanding of the mechanisms associated with the ferroelectric and magnetic phase transitions as well as the correlations between structure, magnetism and ferroelectricity, are still under debate. The aim of this proposal is to perform temperature dependent high resolution powder neutron diffraction in Bi0.7La0.3FeO3, in order to study its crystalline and magnetic structures. From the experimental results, we aim at determining the symmetry and the temperature dependence of wavevector of the modulated phases, the structural distortions associated with the ferroelectric and ferromagnetic phase transitions, and evaluate spin-lattice co
DOI: 10.5286/isis.e.rb1620006
title: Muon spin relaxation study of CDW and superconducting states in LaPt2Si2

description: Coexistence of charge density wave (CDW) and superconductivity (SC) is a long standing puzzle in condensed matter physics. LaPt2Si2 exhibits CDW transition at 112 K followed by a SC transition at 1.7 K. The CDW feature in LaPt2Si2 is quite evident from electrical resistivity, magnetic susceptibility and heat capacity measurements at TCD= 112 K. Moreover, the bulk nature of SC transition is also confirmed by a sharp anomaly in heat capacity at TC ~1.7 K. We anticipate unconventional nature of superconductivity in LaPt2Si2 due to interplay between CDW and superconductivity. We, therefore, propose to carry out rigorous µSR study on LaPt2Si2 using MUSR spectrometer.
DOI: 10.5286/isis.e.rb1620282
title: Unravelling the temperature-pressure phase diagram for the multiferroic, BiFeO3

description: Bismuth ferrite is arguably the most widely studied multiferroic material due to room temperature magnetic and ferroelectric ordering. However, despite extensive research the temperature-pressure phase diagram remains a mystery. We propose to collect data as a function of both temperature and pressure to begin to understand the complex phase evolution in this material. We believe that this will not only provide us with an enhanced understanding of the structure-property correlations in bismuth ferrite but also provide a greater understanding of the as yet undetermined gamma-phase.
DOI: 10.5286/isis.e.rb1620312
title: A high temperature neutron powder diffraction study of the crystal structures and intersite disorder of Cu2ZnSnS4

description: Cu2ZnSnS4 (CZTS) is a solar cell material of great interest. However the material whenfabricated, although of high symmetry, contains substantial defect concentration and a highdegree of atomic mixing on different crystallographic sites. A lack of knowledge regarding thestructure is currently hampering progress on this material. X-ray measurements have shown aniondisplacement changes begin around 420 K with a phase transition between the low-temperaturekesterite structure and a high-temperature sphalerite structure at 1149 K. In the region 1136-1161K a two-phase region occurs with both phases coexisting around the first order phase transition.We propose to undertake high-resolution neutron powder diffraction study to fully characterise thematerial from 300 K to 1200 K using HRPD.
DOI: 10.5286/isis.e.rb1620320
title: Magnetic fluctuations in the presence of charge order  RbFe2+Fe3+F6

description: We propose to investigate the magnetic fluctuations in a charge ordered magnet.  Rb(Fe2+Fe3+)F6 is loosely based on a distorted Kagome framework with alternating chains of ordered Fe2+ and Fe3+ ions.  This compound is therefore charge ordered and also displays magnetic order on both sites below 16 K.  Strong diffuse scattering from fluctuations is present at higher temperatures.  Merlin is required given that momentum maps are required to understand the interactions and dimensionality.  Full three dimensional angular scans will be required.  The proposal requests 5 days on Merlin.
DOI: 10.5286/isis.e.rb1620350
title: Pairing symmetry in superconductors derived from topological insulators (Sr0.1Bi2Se3)

description: Topological insulators are exotic field of study because of presence of fully gapped bulk states and gap less surface states protected by Time Reversal Symmetry (TRS). Occurrence of superconductivity in this wonderful system of materials tantalized condense matter field as only handful of materials are found to exhibit topological superconductivity like Cu,Nb,Sr intercalated Bi2Se3;Tl incorporated Bi2Te3; In doped SnTe. The mechanism for occurrence of superconductivity and pairing symmetry is still a topic of debate. Muon spectroscopy in Zero Field and Transverse Field mode can provide the evidence of unconventional superconductivity along with pairing symmetry and London penetration depth. Our Sr0.1Bi2Se3 sample with large volume fraction is ideal for MuSR study to detect the presence of unconventional superconductivity along with pairing symmetry in this class of materials.
DOI: 10.5286/isis.e.rb1700035
title: Search for magnetic Weyl semimetal in Eu3PbO

description: Materials with nontrivial topological properties (analogous in a general way to the familiar Moebius strip) are a hot topic in current solid state physics. In particular new materials showing different classes of topologically nontrivial electronic states are intensively searched for. Our calculations predict that the inverse perovskite Eu3PbO may display a new type of Weyl point in the electronic structure (namely a 'magnetic Weyl point') brought about by different structural and magnetic properties than in previously discovered Weyl systems. By looking at the details of the magnetism in Eu3PbO using WISH we will be able to confirm whether the predictions of our calculations are correct. This will be critical in determining whether Eu3PbO is the first material to be discovered to contain a 'magnetic Weyl point' and will have important consequences for this very active research field.
DOI: 10.5286/isis.e.rb1710036
title: Better understanding of self-linking behaviour of smectite clays

description: This proposed work is aimed at investigating self-linking behaviour of smectite clays in aqueous suspension. The mechanism of the interaction could be understood by applying VESUVIO spectrometer at ISIS to investigate gelling behaviour of clays in aqueous suspensions. Understanding of this behaviour is concerned directly with several cutting edge material developments including ultra-light weight thermal resistant materials, completely fire resistant and thermal insulation materials, new generation reinforcement materials to achieve high strength, stiffness and toughness in one material system and high efficient dielectric material. Advances of research in these areas will have significant impact on the development of better future aerospace products, safe and energy efficient building, desirable bio-implant components and new generation power generation and transport devices.
DOI: 10.5286/isis.e.rb1710065
title: Micellization in mixtures of surfactants used in fire-fighting foams

description: The aim is to probe the mixed micellar compositions of three common industrial fluorotelomer surfactants used in fire-fighting foam formulations (Figure 1) using contrast variation SANS. These surfactants have already been studied individually (Figure 1) and now will be studied as mixed systems (2- and 3-component systems) over both a range of mole ratios and a range of typical compositions found in fire-fighting foam formulations. The data will allow us to understand how the surfactant aggregation is affected by mixing so as to provide new understanding on the colloidal properties of these practical surfactants. This is the second stage in a new 3-year program, including SANS, so that F-carbon surfactants can be replaced by more environmentally-responsive low-F or hydrocarbon analogues. Chris Hill is a 2nd year PhD student fully funded by fire-fighting technology company Angus Fire.
DOI: 10.5286/isis.e.rb1710145
title: Structures of new n-type thermoelectric oxides

description: Thermoelectric materials (TEs), which produce a voltage in response to an applied temperature gradient, are set to play an increasingly important role in the development of new energy efficient technologies by generating electrical current from waste heat. A performance gap exists between p-type and n-type oxide TEs, which presents a severe limiting factor on the application of oxide-based devices. We are attempting to develop new n-type oxide TEs with competitive ZT values by introducing complex structural ordering to suppress the lattice contribution to thermal conductivity, and by using chemical substitution to increase electrical conductivity, in four oxide solid solutions. We use neutrons to obtain accurate positions for oxide ions within the structures, and require high resolution data to solve the new crystal structures we have produced, and thus to understand their properties.
DOI: 10.5286/isis.e.rb1710187
title: muSR study of a pi-electron S = ½ candidate quantum spin-liquid state in an ionic polyaromatic hydrocarbon (PAH)

description: Molecular solids whose cooperative electronic properties are based purely on pi-electrons from carbon atoms offer a fertile ground in the search for exotic states of matter, including unconventional superconductivity and quantum magnetism. The binary caesium salt of phenanthrene, Cs(C14H10) is a Heisenberg antiferromagnet with a candidate gapped spin-liquid state emerging from the highly-frustrated Delta-chain magnetic topology of coupled alternating-exchange spiral tubes of S=½ (C14H10)- radical anions. The absence of long-range magnetic order down to 1.8 K (T/J~0.02) renders the compound an excellent candidate of a spin-½ quantum spin liquid arising purely from carbon pi-electrons. With this proposal we want to address the nature of the magnetic state down to mK temperatures using the ZF/LF muSR techniqueand search for the emergence or not of long-range antiferromagnetic order.