Structure of alumina glass

AbstractThe fabrication of novel oxide glass is a challenging topic in glass science. Alumina (Al2O3) glass cannot be fabricated by a conventional melt–quenching method, since Al2O3 is not a glass former. We found that amorphous Al2O3 synthesized by the electrochemical anodization of aluminum metal shows a glass transition. The neutron diffraction pattern of the glass exhibits an extremely sharp diffraction peak owing to the significantly dense packing of oxygen atoms. Structural modeling based on X-ray/neutron diffraction and NMR data suggests that the average Al–O coordination number is 4.66 and confirms the formation of OAl3 triclusters associated with the large contribution of edge-sharing Al–O polyhedra. The formation of edge-sharing AlO5 and AlO6 polyhedra is completely outside of the corner-sharing tetrahedra motif in Zachariasen’s conventional glass formation concept. We show that the electrochemical anodization method leads to a new path for fabricating novel single-component oxide glasses.

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The structure of oxide glasses studied by high-energy x-ray diffraction

Physics and Chemistry of Glasses European Journal of Glass Science and Technology Part B ◽

10.13036/17533562.61.6.kohara ◽

2020 ◽

Vol 61 (6) ◽

pp. 233-238

Author(s):

S. Kohara ◽

◽

N. Umesaki ◽

H. Ohno ◽

K. Suzuya ◽

...

Keyword(s):

Neutron Diffraction ◽

Structural Information ◽

Structural Models ◽

High Energy ◽

Reverse Monte Carlo ◽

Oxide Glasses ◽

Neutron Diffraction Data ◽

X Ray Diffraction ◽

X Ray ◽

Approaches To Study

The use of high‑energy x‑ray diffraction techniques with the latest generation synchrotron sources has created new approaches to study quantitatively the structure of noncrystalline materials. Recently, this technique has been combined with neutron diffraction at pulsed source to provide more detailed and reliable structural information not previously available. This article reviews and summarises recent results obtained from the high energy x‑ray diffraction on several oxide glasses, SiO2, B2O3 and PbSiO3, using bending magnet beamlines at SPring‑8. In particular, it addresses the structural models of the oxide glasses obtained by the reverse Monte Carlo (RMC) modelling technique using both the high energy x‑ray and neutron diffraction data.

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Amorphous boron oxide at megabar pressures via inelastic X-ray scattering

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1800777115 ◽

2018 ◽

Vol 115 (23) ◽

pp. 5855-5860 ◽

Cited By ~ 10

Author(s):

Sung Keun Lee ◽

Yong-Hyun Kim ◽

Paul Chow ◽

Yunming Xiao ◽

Cheng Ji ◽

...

Keyword(s):

Oxide Glass ◽

X Rays ◽

Oxide Glasses ◽

Earth’S Core ◽

Earth's Core ◽

X Ray ◽

Mantle Boundary ◽

Core Mantle Boundary ◽

X Ray Scattering ◽

Ray Scattering

Structural transition in amorphous oxides, including glasses, under extreme compression above megabar pressures (>1 million atmospheric pressure, 100 GPa) results in unique densification paths that differ from those in crystals. Experimentally verifying the atomistic origins of such densifications beyond 100 GPa remains unknown. Progress in inelastic X-ray scattering (IXS) provided insights into the pressure-induced bonding changes in oxide glasses; however, IXS has a signal intensity several orders of magnitude smaller than that of elastic X-rays, posing challenges for probing glass structures above 100 GPa near the Earth’s core–mantle boundary. Here, we report megabar IXS spectra for prototypical B2O3 glasses at high pressure up to ∼120 GPa, where it is found that only four-coordinated boron ([4]B) is prevalent. The reduction in the [4]B–O length up to 120 GPa is minor, indicating the extended stability of sp3-bonded [4]B. In contrast, a substantial decrease in the average O–O distance upon compression is revealed, suggesting that the densification in B2O3 glasses is primarily due to O–O distance reduction without the formation of [5]B. Together with earlier results with other archetypal oxide glasses, such as SiO2 and GeO2, the current results confirm that the transition pressure of the formation of highly coordinated framework cations systematically increases with the decreasing atomic radius of the cations. These observations highlight a new opportunity to study the structure of oxide glass above megabar pressures, yielding the atomistic origins of densification in melts at the Earth’s core–mantle boundary.

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Neutron and X-ray scattering from aqueous solutions

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1975.0128 ◽

1975 ◽

Vol 345 (1640) ◽

pp. 107-117 ◽

Cited By ~ 16

Keyword(s):

Aqueous Solution ◽

Neutron Diffraction ◽

Pair Correlation ◽

Neutron Diffraction Pattern ◽

Structural Features ◽

Local Order ◽

Isotopic Substitution ◽

Isotopic Enrichment ◽

X Ray ◽

X Ray Scattering

The total X-ray or neutron diffraction pattern from an aqueous solution containing a salt dissolved in water represents an average of all ten pair correlation functions for the system. As such, it is a complicated quantity and difficult to interpret in terms of the local order. Recently, however, the techniques of isotopic enrichment have been combined with neutron diffraction to isolate particular structural features. In this paper the complementary roles of X-ray and of neutron diffraction combined with isotopic substitution will be emphasized.

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Structure of oxide glasses by synchrotron X-ray and neutron diffraction

hamon ◽

10.5611/hamon.13.51 ◽

2003 ◽

Vol 13 (1) ◽

pp. 51-55

Author(s):

Kentaro Suzuya

Keyword(s):

Neutron Diffraction ◽

Oxide Glasses ◽

X Ray

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Halide Glasses

MRS Bulletin ◽

10.1557/s0883769400067506 ◽

1987 ◽

Vol 12 (5) ◽

pp. 40-44 ◽

Cited By ~ 4

Author(s):

Cornelius T. Moynihan

Keyword(s):

Practical Interest ◽

Chemical Durability ◽

Oxide Glass ◽

Oxide Glasses ◽

Research Activity ◽

Science And Engineering ◽

Laser Applications ◽

Materials Properties ◽

The Past ◽

Glass Science

The term “halide glass” refers to glasses in which the anions are from elements in Group VIIA of the periodic table, namely, F, Cl, Br and I, as opposed, for example, to “oxide glasses,” such as silicates, borates, phosphates, etc. Two known single component halide melts are glassforming, BeF2 and ZnCl2, but the majority of halide glasses are multicomponent. Practical interest in halide glasses has been generated almost entirely by their optical properties, which cannot be duplicated in a more conventional oxide glass. Barriers to the practical deployment of halide glasses have their origin in materials properties in which they can be markedly inferior to oxide glasses, e.g., mechanical strength, resistance of the melt to crystallization, chemical durability, etc.In the past decade there has been considerable and accelerating research activity in the area of halide glass science and engineering. Halide glass research up to 1980 has been reviewed by Baldwin et al. and oxide and halide glasses for laser applications have been compared by Weber. Four international symposia on halide glass science and engineering have been held in the period 1982–1987, the proceedings of the last two of which have been or will be shortly published. The proceedings of a 1986 NATO-sponsored meeting on halide glasses have also been published in book form.

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Texture measurements in Al2O3 using BEKP

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170773 ◽

1994 ◽

Vol 52 ◽

pp. 608-609

Author(s):

M. D. Vaudin ◽

J. P. Cline

Keyword(s):

Neutron Diffraction ◽

Rapid Method ◽

Crystallographic Orientation ◽

Specimen Surface ◽

X Ray Diffraction ◽

Anisotropic Crystal ◽

X Ray ◽

Verification Method ◽

Crystal Properties ◽

Backscattered Electron

The study of preferred crystallographic orientation (texture) in ceramics is assuming greater importance as their anisotropic crystal properties are being used to advantage in an increasing number of applications. The quantification of texture by a reliable and rapid method is required. Analysis of backscattered electron Kikuchi patterns (BEKPs) can be used to provide the crystallographic orientation of as many grains as time and resources allow. The technique is relatively slow, particularly for noncubic materials, but the data are more accurate than any comparable technique when a sufficient number of grains are analyzed. Thus, BEKP is well-suited as a verification method for data obtained in faster ways, such as x-ray or neutron diffraction. We have compared texture data obtained using BEKP, x-ray diffraction and neutron diffraction. Alumina specimens displaying differing levels of axisymmetric (0001) texture normal to the specimen surface were investigated.BEKP patterns were obtained from about a hundred grains selected at random in each specimen.

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METROPOLIS MONTE CARLO X-RAY AND NEUTRON DIFFRACTION IN ICE Ih

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1987102 ◽

1987 ◽

Vol 48 (C1) ◽

pp. C1-9-C1-14 ◽

Cited By ~ 2

Author(s):

P. W. DEUTSCH

Keyword(s):

Monte Carlo ◽

Neutron Diffraction ◽

X Ray ◽

Metropolis Monte Carlo

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Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

10.26434/chemrxiv.12212927 ◽

2020 ◽

Author(s):

Marat Korsik ◽

Edwin Tse ◽

David Smith ◽

William Lewis ◽

Peter J. Rutledge ◽

...

Keyword(s):

Heterocyclic Ring ◽

Ring System ◽

Substitution Reactions ◽

Laboratory Notebook ◽

Polar Solvents ◽

X Ray ◽

X Ray Crystallography ◽

The Core ◽

Nmr Data

We have discovered and studied a telesubstitution reaction in a biologically important heterocyclic ring system. Conditions that favour the tele-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the in vivo active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium. Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds.

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X-ray and Neutron Study on the Structure of Hydrous SiO2 Glass up to 10 GPa

Minerals ◽

10.3390/min10010084 ◽

2020 ◽

Vol 10 (1) ◽

pp. 84 ◽

Cited By ~ 2

Author(s):

Satoru Urakawa ◽

Toru Inoue ◽

Takanori Hattori ◽

Asami Sano-Furukawa ◽

Shinji Kohara ◽

...

Keyword(s):

Oxide Glasses ◽

Void Space ◽

X Ray Diffraction ◽

Amorphous Sio2 ◽

Sio2 Glass ◽

X Ray ◽

X Ray Scattering ◽

Medium Range ◽

Two Phases ◽

A Minor

The structure of hydrous amorphous SiO2 is fundamental in order to investigate the effects of water on the physicochemical properties of oxide glasses and magma. The hydrous SiO2 glass with 13 wt.% D2O was synthesized under high-pressure and high-temperature conditions and its structure was investigated by small angle X-ray scattering, X-ray diffraction, and neutron diffraction experiments at pressures of up to 10 GPa and room temperature. This hydrous glass is separated into two phases: a major phase rich in SiO2 and a minor phase rich in D2O molecules distributed as small domains with dimensions of less than 100 Å. Medium-range order of the hydrous glass shrinks compared to the anhydrous SiO2 glass by disruption of SiO4 linkage due to the formation of Si–OD deuterioxyl, while the response of its structure to pressure is almost the same as that of the anhydrous SiO2 glass. Most of D2O molecules are in the small domains and hardly penetrate into the void space in the ring consisting of SiO4 tetrahedra.

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