Coordination chemistry of Ti(IV) in silicate glasses and melts: I. XAFS study of titanium coordination in oxide model compounds

Farges, François; Brown, Gordon E.; Rehr, J. J.

doi:10.1016/0016-7037(96)00144-5

Cited by 305 publications

(368 citation statements)

References 67 publications

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“…Electrochemical series show that titanium is expected to occur in oxide glasses produced under oxidising conditions entirely as Ti 4+ [39]. Coordination of Ti 4+ in oxide glasses has been studied extensively by Farges and colleagues [43][44][45], who concluded that Ti 4+ occurs predominantly as [5] Ti 4+ in a wide range of oxide glasses. We have therefore assumed for our models that Ti 4+ occurs as 50% [4] Ti 4+ and 50% [6] Ti 4+ in…”

Section: +mentioning

confidence: 99%

Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses

Bingham

Vaishnav

Forder

et al. 2017

Journal of Alloys and Compounds

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(2017). Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses. Journal of Alloys and Compounds, 695,[656][657][658][659][660][661][662][663][664][665][666][667]. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Copyright and re-use policy M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT

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Section: +mentioning

confidence: 99%

Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses

Bingham

Vaishnav

Forder

et al. 2017

Journal of Alloys and Compounds

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“…These uncertainties are caused in part by the fact that tetravalent titanium shows variable coordination with oxygen in silicate melts as well as hydrous fluids (Farges et al, 1996;Romano et al, 2000;Liu and Lange, 2001;Guillot and Sator, 2007;Van Sijl et al, 2010). In the case of silicate melts, this has an important effect on the melt properties.…”

Section: The Effect Of Titanium On Melt Density and Compressibilitymentioning

confidence: 99%

Compressibility of molten Apollo 17 orange glass and implications for density crossovers in the lunar mantle

Parker

Agee

Duncan

et al. 2011

Geochimica et Cosmochimica Acta

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We performed density measurements on a synthetic equivalent of lunar Apollo 17 74,220 "orange glass", containing 9.1 wt% TiO 2 , at superliquidus conditions in the pressure range 0.5-8.5 GPa and temperature range 1723-2223 K using the sink/float technique. In the lunar pressure range, two experiments containing pure forsterite (Fo 100 ) spheres at 1.0 GPa and 1727 K, and at 1.3 GPa-1739 K, showed neutral buoyancies, indicating that the density of molten orange glass was equal to the density of Fo 100 at these conditions (3.09 ± 0.02 g cm À3 ). A third tight sink/float bracket using Fo 90 spheres corresponds to a melt density of 3.25 ± 0.02 g cm À3 at $2.8 GPa and $1838 K.Our data predict a density crossover for the molten orange glass composition with equilibrium orthopyroxene at $2.8 GPa, equivalent to a depth of $600 km in the lunar mantle, and a density of $3.25 g cm À3 . This crossover depth is close to the orange glass multiple saturation point, representing its minimum formation depth, at the appropriate oxygen fugacity (2.8-2.9 GPa). A density crossover with equilibrium olivine is predicted to fall outside the lunar pressure range (>4.7 GPa), indicating that molten orange glass is always less dense than its equilibrium olivines in the Moon. Our data therefore suggest that that lunar liquids with orange glass composition are buoyant with respect to their source region at P < $2.8 GPa, enabling their initial rise to the surface without the need for additional external driving forces.Fitting the density data to a Birch-Murnaghan equation of state at 2173 K leads to an array of acceptable solutions ranging between 16.1 and 20.3 GPa for the isothermal bulk modulus K 2173 and 3.6-8 for its pressure derivative K 0 , with best-fit values K 2173 = 18.8 GPa and K 0 = 4.4 when assuming a model 1 bar density value of 2.86 g cm À3 . When assuming a slightly lower 1 bar density value of 2.84 g cm À3 we find a range for K 2173 of 14.4-18.0 and K 0 3.7-8.7, with best-fit values of 17.2 GPa and 4.5, respectively.

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“…14) Another Raman spectral study conducted by Mysen et al 15) showed coexistence of six-fold and four-fold coordinated titanium, and four-fold titanium increases with increase of TiO 2 content. Raman and infrared spectral study by Bihuniak et al 16) showed that titanium is present in four-fold coordination in titanium-containing vitreous silicas, while X-ray Absorption Fine Spectra(XAFS) 17) and neutron diffraction 18) study showed dominant five-fold titanium existence in some glasses and melts. Regarding fluorine in structure of glass, 19 F nuclear magnetic resonance with magic angular spinning (MAS-NMR) study show that most fluoride is in sites that are structurally similar to the corresponding simple metal fluoride and a few present of Si-F bonds can be founded in the sodium silicates.…”

Section: Introductionmentioning

confidence: 99%

Structural Study of Glassy CaO–SiO2–CaF2–TiO2 Slags by Raman Spectroscopy and MAS-NMR

Shu

Chou

2014

ISIJ Int.

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During the production of titanium stabilized stainless steel, as titanium in steel has a tendency to reacting with SiO2 in mould fluxes to generate TiO2 into mould fluxes and mould powder can inevitably pick up Ti-bearing inclusions floating up from steel, TiO2 content in the molten mould fluxes gradually increases so that physiochemical properties of the fluxes change. To evaluate the effect of TiO2 increase in mould fluxes on the structure of the mould flux, the glassy slag system CaO-SiO2-CaF2-TiO2 for stainless steel casting fluxes was studied by combining Raman spectroscopy with 29 in tetrahedral coordination, which cannot change the degree of polymerization of the silicate network. A small amount of Ti enters into the silicate network as the role of network formation, which slightly enhances the degree of polymerization of the silicate network. According to 19 F MAS-NMR spectra, most of the fluorine is exclusively coordinated by Ca 2+ corresponding to F-Ca(n) site and only a few Si-F bonds were observed in samples. Increase of TiO2 content has no significant effects on the F-bonds.

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Coordination chemistry of Ti(IV) in silicate glasses and melts: I. XAFS study of titanium coordination in oxide model compounds

Cited by 305 publications

References 67 publications

Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses

Modelling the sulfate capacity of simulated radioactive waste borosilicate glasses

Compressibility of molten Apollo 17 orange glass and implications for density crossovers in the lunar mantle

Structural Study of Glassy CaO–SiO2–CaF2–TiO2 Slags by Raman Spectroscopy and MAS-NMR

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