Journal ArticleDOI
Structure of densified vitreous silica: silicon and oxygen XANES spectra and multiple scattering calculations
Ivan Davoli,Eleonora Paris,Sergio Stizza,Maurizio Benfatto,M. Fanfoni,A. Gargano,Antonio Bianconi,Friedrich Seifert +7 more
- Vol. 19, Iss: 3, pp 171-175
TLDR
In this article, multiple scattering calculations using clusters of two shells around the oxygen and silicon atoms, respectively, are in good agreement with experimental absorption spectra and confirm mean Si-O-Si angles between 130 and 144° for these samples, and a decrease of the mean angle with densification.Abstract:
The decrease of the mean Si-O-Si angle in vitreous silica upon densification from 2.20 to 2.36 gcm-3 has been followed by oxygen and silicon K-edge XANES spectroscopy. Multiple scattering calculations using clusters of two shells around the oxygen and silicon atoms, respectively, are in good agreement with experimental absorption spectra and confirm mean Si-O-Si angles between 130 and 144° for these samples, and a decrease of the mean angle with densification. The experimental spectra also exhibit features due to scattering at outer (>2) shells around the photoabsorbers.read more
Citations
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Journal ArticleDOI
Nanoscale chemical imaging of a working catalyst by scanning transmission X-ray microscopy
Emiel de Smit,Ingmar Swart,J. Fredrik Creemer,Gerard H. Hoveling,Mary K. Gilles,Tolek Tyliszczak,Patricia J. Kooyman,Henny W. Zandbergen,Cynthia Morin,Bert M. Weckhuysen,Frank M. F. de Groot +10 more
TL;DR: Scanning transmission X-ray microscopy can be used at atmospheric pressure and up to 350 °C to monitor in situ phase changes in a complex iron-based Fisher–Tropsch catalyst and the nature and location of carbon species produced.
Journal ArticleDOI
Oxygen K-edge X-ray Absorption Spectra
TL;DR: Oxygen K-edge X-ray absorption spectra of both molecules and solids and the general analysis of the 3d transition metal oxides including discussions of the crystal field effect and the effects and trends in oxidation state and covalency are discussed.
Journal ArticleDOI
X-ray absorption near-edge structure (XANES) spectroscopy
TL;DR: X-ray absorption near-edge structure (XANES) spectroscopy using synchrotron radiation is a well-established technique providing information on the electronic, structural and magnetic properties of matter as discussed by the authors.
Journal ArticleDOI
X-ray Raman scattering study of MgSiO3 glass at high pressure: Implication for triclustered MgSiO3 melt in Earth's mantle
Sung Keun Lee,Jung-Fu Lin,Yong Q. Cai,Nozomu Hiraoka,Peter J. Eng,Takuo Okuchi,Ho-kwang Mao,Ho-kwang Mao,Yue Meng,Yue Meng,Michael Y. Hu,Paul Chow,Jinfu Shu,Baosheng Li,Hiroshi Fukui,Bum Han Lee,Hyun Na Kim,Choong-Shik Yoo +17 more
TL;DR: The results indicate that the densification in MgSiO3 melt is thus likely to be accompanied with the formation of triculster, in addition to a reduction in nonbridging oxygens, and the pressure-induced increase in the fraction of oxygen triclusters >20 GPa would result in enhanced density, viscosity, and crystal-melt partitioning, and reduced element diffusivity in the M gSiO2 melt toward deeper part of the Earth
Journal ArticleDOI
A Raman spectroscopic study of shock-wave densification of vitreous silica
TL;DR: In this article, the densification process in SiO2 glass induced by shock-wave compression up to 43.4 GPa was investigated by Raman spectroscopy, where the authors attributed the reduction of the average Si−O−Si angle to the collapse of the largest ring cavities.
References
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Journal ArticleDOI
The structure of vitreous silica
R. L. Mozzi,B. E. Warren +1 more
TL;DR: In this paper, a new study of the structure of vitreous silica has been made under greatly improved conditions, using Rh Kα radiation with the method of fluorescence excitation, reliable intensity values were measured to 4π sinθ/λ = 20.
Journal Article
Structure and elastic properties of quartz at pressure
TL;DR: In this paper, unit cells and crystal structures were determined on a single crystal of quartz at seven pressures from I atm to 61.4 kbar by fitting the P-V data to a Birch-Murnaghan equation of state.
Journal Article
Three-dimensional network structure of quenched melts (glass) in the systems SiO 2 -NaAlO 2 , SiO 2 -CaAl 2 O 4 and SiO 2 -MgAl 2 O 4
Journal ArticleDOI
Compression mechanisms in α‐quartz structures—SiO2 and GeO2
TL;DR: In this article, the authors measured the interatomic distances and angles for the α-quartz forms of SiO2 and GeO2 using time-of-flight powder neutron diffraction.