A5020949186- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Crystallization and Solubility Studies
- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Spectroscopy and Quantum Chemical Studies
- X-ray Diffraction in Crystallography
- Advancements in Battery Materials
- Crystal Structures and Properties
- Chemical and Physical Properties in Aqueous Solutions
- Multiferroics and related materials
- Inorganic Chemistry and Materials
- Advanced Battery Materials and Technologies
- Electron and X-Ray Spectroscopy Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- High-pressure geophysics and materials
- Inorganic Fluorides and Related Compounds
- Catalytic Processes in Materials Science
- Molecular spectroscopy and chirality
- Radioactive element chemistry and processing
- Advanced NMR Techniques and Applications
- Theoretical and Computational Physics
- Corporate Taxation and Avoidance
- Superconducting Materials and Applications
University of Kent
2014-2023
Diamond Light Source
2009-2019
University of Oxford
2012-2015
University of Birmingham
2006-2012
University of Bristol
2000-2005
European Synchrotron Radiation Facility
2001-2005
Conventional intercalation cathodes for lithium batteries store charge in redox reactions associated with the transition metal cations, e.g., Mn3+/4+ LiMn2O4, and this limits energy storage of Li-ion batteries. Compounds such as Li[Li0.2Ni0.2Mn0.6]O2 exhibit a capacity to excess reactions. The additional occurs at above 4.5 V versus Li+/Li. is dominated by oxidation O2– anions accounting ∼0.43 e–/formula unit, an 0.06 unit being O loss from lattice. In contrast, mainly loss, ∼0.08...
It is possible to increase the charge capacity of transition-metal (TM) oxide cathodes in alkali-ion batteries by invoking redox reactions on oxygen. However, oxygen loss often occurs. To explore what affects materials, we have compared two analogous Na-ion cathodes, P2-Na0.67Mg0.28Mn0.72O2 and P2-Na0.78Li0.25Mn0.75O2. On charging 4.5 V, >0.4e– are removed from ions these but neither compound exhibits loss. Li retained P2-Na0.78Li0.25Mn0.75O2 displaced TM alkali metal layers, showing that...
During the past twenty years, XAS has progressed from being a technique only suitable for specialists to become widely applicable tool. This situation resulted steady development of reliable spectrometers and new generations software data analysis. B18 will be general purpose beamline on Diamond. It cover wide energy range (2 35 keV), with monochromator designed carry out both conventional QEXAFS measurements. The main design novelty is that low high optic branches run in parallel...
Hydrothermal synthesis is described of layered lithium iron selenide hydroxides Li(1-x)Fe(x)(OH)Fe(1-y)Se (x ∼ 0.2; 0.02 < y 0.15) with a wide range site vacancy concentrations in the layers. This concentration revealed as only significant compositional variable and key parameter controlling crystal structure electronic properties. Single X-ray diffraction, neutron powder absorption spectroscopy measurements are used to demonstrate that superconductivity at temperatures high 40 K observed...
Ionic conductivity is ubiquitous to many industrially important applications such as fuel cells, batteries, sensors, and catalysis. Tunable in these systems therefore key their commercial viability. Here, we show that geometric frustration can be exploited a vehicle for tuning. In particular, imposed upon prototypical system, CaF2, by ball milling it with BaF2, create nanostructured Ba1–xCaxF2 solid solutions increased its ionic over 5 orders of magnitude. By mirroring each experiment MD...
The presence of ions and/or apolar species in water provides a rich and varied environment which many natural processes occur.This review results recent structural studies aqueous solutions derived from state–of–the–art neutron X–ray scattering methods. enhanced resolution provided by methods such as diffraction isotopic substitution, anomalous diffraction, have given scientists new insights into the contrasting hydration structures variety small molecules, crucially how these might affect...
The change in structure of glassy GeS(2) with pressure increasing to [Formula: see text] at ambient temperature was explored by using situ neutron and x-ray diffraction. Under conditions, the glass is made from a mixture corner- edge-sharing Ge(S(1/2))(4) tetrahedra where 47(5)% Ge atoms are involved configurations. network formed these orders on an intermediate range as manifested appearance pronounced first sharp diffraction peak measured total factors scattering vector k = 1.02(2) Å(-1)...
In this study, we report the application of synchrotron radiation microprobe to analysis Mn-rich clusters in GaN. From Mn and Ga fluorescence line intensity ratio, an average concentration 11% was deduced. A combination mapping with spectroscopic techniques enabled us examine not only cluster elemental nature but also their crystallographic orientation on submicron scale. The strong polarization-dependent x-ray absorption near-edge structure features showed preservation hexagonal symmetry...
Reduction of La(1-x)Ca(x)MnO(3) (0.6 ≤ x 1) perovskite phases with sodium hydride yields materials composition La(1-x)Ca(x)MnO(2+δ). The calcium-rich (x = 0.9, adopt (La(0.9)Ca(0.1))(0.5)Mn(0.5)O disordered rocksalt structures. However local structure analysis using reverse Monte Carlo refinement models against pair distribution functions obtained from neutron total scattering data reveals lanthanum-rich La(1-x)Ca(x)MnO(2+δ) 0.6, 0.67, 0.7) structures consisting an intergrowth sheets MnO(6)...
H/D isotopic substitution neutron scattering and X-ray have been used to investigate the short intermediate range solution structure in a 1 m aqueous of lanthanum chloride. To improve reliability local structural information on cation environment, has incorporated from Extended Absorption Fine Structure (EXAFS) spectroscopy data into applied analytical framework. The markedly different sensitivities experimental probes allow construction detailed three-dimensional atomistic model using...
B18 has been operational since April 2010 and hosted a total of 63 EXAFS user experiments up to Jan 2012. is contributing research programs across wide range scientific disciplines, e.g. solid state physics materials, catalysis, chemistry, soft matter, surfaces biomaterials. We present review its performance capabilities.
The Na<sub>x</sub>[Ni<sub>(x−y)/2</sub>Mn<sub>(2−x−y)/2</sub>Fe<sub>y</sub>]O<sub>2</sub> composition space was explored, and two compositions were identified as P2 compounds that can deliver high energy densities.
We report an extensive investigation of magnetic vortex lattice (VL) structures in single crystals pure niobium with the field applied parallel to a fourfold symmetry axis, so as induce frustration between cubic crystal and hexagonal VL coordination expected isotropic situation. observe new phase transitions; all phases observed (including those exactly square unit cell) spontaneously break some symmetry. One even has lowest possible two-dimensional Bravais lattice. This is quite unlike...
The hydrothermal oxidation of Ce3+ in basic aqueous solution by NaBiVO3 at 240 °C produces fine powders cerium−bismuth oxides with crystallite sizes less than 10 nm, as observed transmission electron microscopy (TEM). Analysis X-ray absorption near-edge structure the Bi LIII and Ce edges confirms reduction Bi5+ to Bi3+ Ce4+, consistent a general chemical composition CeIV1-xBiIIIxO2-(x/2) (x ≤ 0.6) for mixed oxides. refined cubic lattice parameters from powder neutron diffraction indicate...
We have carried out muon spin relaxation (\ensuremath{\mu}SR), neutron diffraction, and inelastic scattering (INS) investigations on polycrystalline samples of Ce(Ru${}_{1\ensuremath{-}x}$Fe${}_{x}$)${}_{2}$Al${}_{10}$ ($x=0$, 0.3, 0.5, 0.8, 1) to investigate the nature ground state (magnetic ordered versus paramagnetic) origin spin-gap formation as evident from bulk measurements in end members. Our zero-field \ensuremath{\mu}SR spectra clearly reveal coherent two-frequency oscillations at...
High-purity niobium exhibits a surprisingly rich assortment of vortex lattice (VL) structures for fields applied parallel to fourfold symmetry axis, with all observed VL phases made up degenerate domains that spontaneously break some crystal symmetry. Yet single regular hexagonal domain is at temperatures and threefold axis. We report detailed investigation the transition between these lush barren landscapes, discovering new phase transitions high fields. show number relative population...
Anomalous x-ray diffraction experiments were carried out at two energies below the K edge of strontium on a 3.5 molal solution chloride in water. The first order difference method was applied to corrected and normalized data sets, function for Sr2+ coordination obtained. Fourier transformation this gave modified total radial distribution Sr2+, which when analyzed showed that there are eight nine nearest neighbor water molecules sited 2.67 Å from ion. A second shell is also apparent range...
Anomalous x-ray diffraction experiments were carried out on concentrated aqueous solutions of sodium iodide (6 molal) and cesium (3 molal). Data gathered at two energies below the absorption edges Cs+ I- ions in order to avoid contributions from fluorescence. The statistics quality raw data improved by use a focusing analyzer crystal. Differences taken between sets used calculate hydration structures I-. found are more complex than anticipated for such large with relatively low charge...
The low-temperature magnetic behavior of the double-layered ruthenate Sr${}_{3}$Ru${}_{2}$O${}_{7}$, as grown from a eutectic Sr${}_{2}$RuO${}_{4}$-Sr${}_{3}$Ru${}_{2}$O${}_{7}$ system, was investigated via zero- and transverse-field muon-spin rotation. gradual increase muon relaxation rate observed below 2.5 K, even in absence applied fields, indicates occurrence spontaneous breaking time-reversal symmetry. onset latter at temperature above 1.5 ${T}_{c}$ single phase Sr${}_{2}$RuO${}_{4}$,...