Raman and XANES spectroscopy of permanently densified vitreous silica

Poe, Brent T.; Romano, Claudia; Henderson, Grant S.

doi:10.1016/j.jnoncrysol.2004.04.014

Cited by 59 publications

(59 citation statements)

References 23 publications

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“…Still, considering the spectra from (b) to (f), the intensity of the bands can be evaluated from a quasi-quantitative point of view. In fact, the complex intense feature in the 550-350 cm 1 range, assigned to siliceous bulk vibrational modes, 35 presents a fairly constant Raman intensity and proves, in this way, that the analyzed sample portion is always the same.…”

Section: Resultsmentioning

confidence: 74%

“…In particular, bands at around 430 cm 1 are due to oxygen motions, both in-plane Si-O-Si bending vibrations and out-of-plane rocking motions, while the sharp peak at about 490 cm 1 has been assigned to vibrations involving symmetric breathing motions of fourmembered siloxane rings. 35 At higher wavenumbers, minor features to be ascribed to silica vibrational modes are the discrete bands at 602 and 804 cm 1 , and a component of the large signal around 1000 cm 1 assigned to breathing motions of planar three-membered rings, sym (Si-O) and asym (Si-O) of the Si-O-Si groups, respectively. 35 Vibrational evidences for the presence of Si-O-H groups could also be present in this spectral interval, but they fall in the same range of some of the above-mentioned signals: Raman features centered at about 800 cm 1 can be assigned to υ(SiOH) vibrations and at 976 cm 1 can be assigned to (Si-O) of Si-OH groups.…”

Section: Resultsmentioning

confidence: 99%

“…35 At higher wavenumbers, minor features to be ascribed to silica vibrational modes are the discrete bands at 602 and 804 cm 1 , and a component of the large signal around 1000 cm 1 assigned to breathing motions of planar three-membered rings, sym (Si-O) and asym (Si-O) of the Si-O-Si groups, respectively. 35 Vibrational evidences for the presence of Si-O-H groups could also be present in this spectral interval, but they fall in the same range of some of the above-mentioned signals: Raman features centered at about 800 cm 1 can be assigned to υ(SiOH) vibrations and at 976 cm 1 can be assigned to (Si-O) of Si-OH groups. 36,37 Besides the silica features, in spectrum (a) an intense band is present at 950 cm 1 .…”

Section: Resultsmentioning

confidence: 99%

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In situ Raman study to monitor bioactive glasses reactivity

Bonino

Damin

Aina

et al. 2007

J Raman Spectroscopy

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This work, by means of Raman spectroscopy, studies the vibrational modifications of a silica-based sol-gel bioactive glass (77S) in direct contact with a simple TRIS-buffered solution. The novelty of this contribution with respect to similar previous works consists in the adoption of an in situ setup, designed to avoid all kinds of external contamination. The time-dependent formation of the characteristic vibrational features of surface hydroxy-carbonate apatite (HCA) is evidenced, and followed as a function of contact time.

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Section: Resultsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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In situ Raman study to monitor bioactive glasses reactivity

Bonino

Damin

Aina

et al. 2007

J Raman Spectroscopy

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“…The tetrahedral coordination of Si by four O atoms is a common feature of all silicates and as a consequence both crystalline and amorphous silicates exhibit very similar K-edge XANES (Li et al 1993(Li et al , 1995Wu et al 1998;Poe et al 1997Poe et al , 2004Bender 2002;Henderson & Fleet 1997;Henderson 1995;Farges et al 1999;Thompson et al 1996;Gilbert et al 2003). Typically, all show the strong white line feature G and a broad hump feature K seen in Fig.…”

Section: Si K-edge Xanesmentioning

confidence: 88%

Structural signatures of medium-range order in annealed laboratory silicates

Thompson¹

2008

A&A

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Context. Silicate dust grains exist in a wide range of astronomical environments and understanding the effect of these on grain structure is of great interest, particularly the effect of thermal annealing on amorphous silicates as a possible route to the formation of crystalline grains. Although laboratory simulations have largely focussed on IR-spectroscopic measurements, since these relate directly to observational data, laboratory synchrotron techniques such as X-ray absorption spectroscopy (XAS) and X-ray scattering are becoming increasingly routine in the analysis of recovered materials. With the increasing prospect of performing astronomical XAS observations, there is much to be gained from applying these techniques to laboratory analogues. Aims. Diagnostic markers for medium-range order and the effect of thermal annealing on these in amorphous silicates of differing Mg content are characterised using synchrotron X-ray methods. Methods. Three synthetic amorphous silicates with high, medium and low Mg:Si ratios were annealed at varying temperatures up to 1300 K. X-ray Absorption Near Edge Structure (XANES) spectra at the Si and Mg K-shell absorption edges and X-ray scattering patterns for low values of the X-ray scattering wavevector were recorded for these along with comparative data for commercially produced amorphous SiO 2 and mineral samples of forsterite, enstatite and quartz. Results. XANES features due to short-and medium-range structure are identified at both Mg and Si edges and a new temperature dependent behaviour observed in the medium-range structure surrounding Mg and Si. Based on changes to the morphological details of the XANES spectra, the medium-range structure changes between an enstatite-like and forsterite-like coordination with increasing temperature and appears to correlate directly with Mg content. Low wavevector X-ray scattering features were also found to be diagnostic of the type of medium-range structural ordering. However, these features depend on whether the relative arrangement of clusters of medium-range structure exhibit semi-periodic ordering over the longer-range, which can vary with annealing.

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“…The microstructural changes in silica glass under high pressure have been extensively studied, both experimentally [17][18][19][20][21][22] and using molecular dynamics simulations [23][24][25][26][27][28][29][30]. The first sharp diffraction peak in the X-ray or neutron static structure factor of silica glass was observed to shift to larger scattering factor q and decrease in its magnitude with increasing glass density.…”

Section: Introductionmentioning

confidence: 99%