A5044619719- Glass properties and applications
- Phase-change materials and chalcogenides
- Material Dynamics and Properties
- Solid-state spectroscopy and crystallography
- High-pressure geophysics and materials
- X-ray Diffraction in Crystallography
- Spectroscopy and Quantum Chemical Studies
- Mineralogy and Gemology Studies
- Luminescence Properties of Advanced Materials
- Chemical and Physical Properties in Aqueous Solutions
- Advanced NMR Techniques and Applications
- Crystal Structures and Properties
- Nuclear materials and radiation effects
- Thermodynamic and Structural Properties of Metals and Alloys
- Nuclear Physics and Applications
- Thermodynamic properties of mixtures
- Molten salt chemistry and electrochemical processes
- Advanced Condensed Matter Physics
- Theoretical and Computational Physics
- NMR spectroscopy and applications
- Quantum, superfluid, helium dynamics
- Crystallization and Solubility Studies
- Chalcogenide Semiconductor Thin Films
- Inorganic Fluorides and Related Compounds
- Advanced Chemical Physics Studies
University of Bath
2015-2024
Parliament of United Kingdom
2022
Artemis (United States)
2022
Corning (United States)
2017-2019
University of East Anglia
1989-1999
Institut Langevin
1989
Bristol Robotics Laboratory
1983
University of Bristol
1983
CEA Grenoble
1973-1976
The techniques of neutron diffraction and x-ray diffraction, as applied to structural studies liquids glasses, are reviewed. Emphasis is placed on the explanation discussion experimental data analysis methods, illustrated by results representative experiments. disordered, isotropic nature structure glasses leads special considerations certain difficulties when applied, especially used in combination same system. Recent progress technique, well computer simulation, has motivated writing this review.
We determined the structure of hydrated Cu(II) complex by both neutron diffraction and first-principles molecular dynamics. In contrast with generally accepted picture, which assumes an octahedrally solvated ion, our experimental theoretical results favor fivefold coordination. The simulation reveals that undergoes frequent transformations between square pyramidal trigonal bipyramidal configurations. argue this picture is also consistent data obtained previously visible near-infrared...
The full set of partial structure factors for the prototypical network glass GeSe2 was measured using method isotopic substitution in neutron diffraction. basic building block is Ge(Se(1/2))(4) tetrahedron which 34(5)% Ge reside edge-sharing configurations. intrinsic chemical order is, however, broken with a maximum 25(5)% and 20(5)% Se being involved homopolar bonds at distances 2.42(2) 2.32(2) A, respectively.
The problem of those discernible features the intermediate range order (IRO) which can be attributed to first sharp diffraction peak (FSDP) observed in structure factor many liquid and glassy materials is approached by treating this as a distinct feature. It found, considering measured partial factors, S αβ ( k ), for molten ZnCl 2 , GeSe MgCl NiBr Nil total F SiO PS 4 CCl that propensity FSDP have prominent effect on underlying IRO depends noticeably system type. Specifically, confers...
A combination of in situ high-pressure neutron diffraction at pressures up to 17.5(5) GPa and molecular dynamics simulations employing a many-body interatomic potential model is used investigate the structure cold-compressed silica glass. The give good account results existing x-ray ~60 GPa. On basis results, an atomistic for densification proposed which rings are "zipped" by pairing five- and/or sixfold coordinated Si sites. gives accurate description dependence mean primitive ring size ⟨n⟩...
The structure of liquid alumina at a temperature \ensuremath{\sim}2400 K near its melting point was measured using neutron and high-energy x-ray diffraction by employing containerless aerodynamic--levitation laser-heating techniques. patterns were compared to those calculated from molecular dynamics simulations variety pair potentials, the model found be in best agreement with experiments refined reverse Monte Carlo method. resultant shows that melt is composed predominantly AlO${}_{4}$...
Abstract The broken symmetry in the atomic-scale ordering of glassy versus crystalline solids leads to a daunting challenge provide suitable metrics for describing order within disorder, especially on length scales beyond nearest neighbor that are characterized by rich structural complexity. Here, we address this silica, canonical network-forming glass, using hot cold compression (i) systematically increase after densification and (ii) prepare two glasses with same high-density but...
The first full partial-structure-factor analysis of molten ${\mathrm{GeSe}}_{2}$ is made using the method isotopic substitution in neutron diffraction. It shown that melt comprises roughly equal numbers edge- and corner-sharing tetrahedra which give rise to a highly connected or network liquid. Concentration fluctuations extend over distances characteristic intermediate-range order, contrary results obtained from recently developed effective potentials for covalently bonded glass-forming...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiffraction and the study of aqua ionsJ. E. Enderby, S. Cummings, G. J. Herdman, W. Neilson, P. Salmon, N. SkipperCite this: Phys. Chem. 1987, 91, 23, 5851–5858Publication Date (Print):November 1, 1987Publication History Published online1 May 2002Published inissue 1 November 1987https://pubs.acs.org/doi/10.1021/j100307a008https://doi.org/10.1021/j100307a008research-articleACS PublicationsRequest reuse permissionsArticle...
The structure of heavy and light water at 300 K was investigated by using a joint approach in which the method neutron diffraction with oxygen isotope substitution combined path integral molecular dynamics simulations.The results, give intra-molecular O-D O-H bond distances 0.985(5) 0.990(5) Å, were found to be best agreement those obtained flexible anharmonic TTM3-F model.Both techniques show difference 0.5% between lengths results support competing quantum effects model for its structural...
Significance The structures of liquid and amorphous oxides are difficult to solve because the complexity their disordered networks, adaptability in size oxide ions coordination environments. Particular difficulty is therefore associated with an identification generic features structural transformations. This paper adopts empirical approach find ion size, shows that network a wide variety can be categorized terms oxygen-packing fraction over extensive pressure temperature range. packing...
The pressure-driven collapse in the structure of network-forming materials will be considered gigapascal (GPa) regime, where development situ high-pressure neutron diffraction has enabled this technique to obtain new structural information. improvements methodology are discussed, and complementary nature results is illustrated by considering transformations for several key that have also been investigated using other experimental techniques such as x-ray diffraction, inelastic scattering,...
A systematic analysis of those liquid binary 2:1 systems (denoted MX 2 ), for which experimental partial structure factors are available from the isotopic substitution method in neutron diffraction, is made using Bhatia-Thornton (BT) formalism.Particular attention paid to origin first sharp diffraction peak (FSDP occurs measured patterns some systems, since it appears, recent studies, that this feature a signature directional bonding. It found FSDPS can occur all three BT S xB (k). FSDP...
The partial structure factors of bulk-quenched glassy GeSe2 were measured by using the method isotopic substitution in neutron diffraction to enable first detailed comparison at pair distribution function level a covalently bonded network system both its and liquid phases. results show that basic building block glass is Ge(Se1/2)4 tetrahedron which 34(5)% Ge atoms reside edge-sharing configurations. intrinsic chemical order is, however, broken with maximum 25(5)% 20(5)% Se being involved...
The static structure factor S(k) and pair distribution function g(r) of liquid germanium at 1000 degrees C were measured using neutron diffraction. A wider k-range was covered that in previous diffraction experiments on Ge particular attention given to the data analysis procedure used extra from intensities. has a first peak 2.66+or-0.02 AA gives an averaged coordination number 5.6. results are discussed with reference studies systematic differences between X-ray observed.
The full set of partial structure factors for glassy germania, or GeO2, were accurately measured by using the method isotopic substitution in neutron diffraction order to elucidate nature pair correlations this archetypal strong glass former. results show that basic tetrahedral Ge(O1/2)4 building blocks share corners with a mean inter-tetrahedral Ge-Ô-Ge bond angle 132(2)°. topological and chemical ordering resultant network displays two characteristic length scales at distances greater than...
The hydration structure around chloride ions has been determined for several heavy water electrolyte solutions at various concentrations by the first-order difference method of neutron diffraction. Particular attention focused on aqueous zinc solutions, which results are now available. following conclusions have drawn from these data: (1) chloride-water radial distribution function a similar form in all studied and is consistent with well defined geometry, Cl—D nearest neighbour distance,...
The relation between the fragility of glass-forming systems, a parameter which describes many their key physical characteristics, and atomic scale structure is investigated by using neutron diffraction to measure topological chemical ordering for germania, or ${\mathrm{GeO}}_{2}$, an archetypal strong glass former. We find that this other tetrahedral network-forming glasses at distances greater than nearest neighbor can be rationalized in terms interplay relative importance two length...
The structure of GeO2 glass was investigated at pressures up to 17.5(5) GPa using in situ time-of-flight neutron diffraction with a Paris–Edinburgh press employing sintered diamond anvils. A new methodology and data correction procedure were developed, enabling reliable measurement factors that are largely free from Bragg peaks. Calibration curves, which important for work on disordered materials, constructed pressure as function applied load both single double toroid anvil geometries....
The structure of the fragile glass-forming material CaAl(2)O(4) was measured by applying method neutron diffraction with Ca isotope substitution to laser-heated aerodynamically levitated liquid at 1973(30) K and glass 300(1) K. results, interpreted aid molecular dynamics simulations, reveal key structural modifications on multiple length scales. Specifically, there is a reorganization quenching that leads an almost complete breakdown AlO(5) polyhedra threefold coordinated oxygen atoms...
The pressure-induced changes to the structure of disordered oxide and chalcogenide network-forming materials are investigated on length scales associated with first three peaks in measured diffraction patterns. density dependence a given peak position does not yield network dimensionality, contrast metallic glasses where results indicate fractal geometry local dimensionality $\ensuremath{\simeq}5/2$. For oxides, common relation is found between intermediate-range ordering, as described by...
The method of in situ high-pressure neutron diffraction is used to investigate the structure ${\mathrm{B}}_{2}{\mathrm{O}}_{3}$ glass on compression range from ambient 17.5(5) GPa. experimental results are supplemented by molecular dynamics simulations made using a newly developed aspherical ion model. tie together those obtained other techniques reveal three densification regimes. In first, ${\mathrm{BO}}_{3}$ triangles predominant structural motifs as pressure increased 6.3(5) GPa, but...