Effect of aluminum on Ti-coordination in silicate glasses: A XANES study

Romano, Claudia; Paris, Eleonora; Poe, Brent T.; Giuli, Gabriele; Dingwell, Donald B.; Mottana, Annibale

doi:10.2138/am-2000-0112

Cited by 58 publications

(52 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Sodium silicate glasses have a mix of [4] Ti and [5] Ti up to 14.3 wt% TiO 2 , and then only [5] Ti. Potassium silicate glasses have the same behavior with more [4] Ti, indicating that large alkali cations appear to stabilize a relatively low average Ti coordination number compared to the smaller alkaline-earth cations [12,14].…”

Section: Introductionmentioning

confidence: 91%

“…All methods used to determine the coordination number distribution for Ti atoms agree on the predominance of [5] Ti, with the coexistence of [4] Ti and [6] Ti in similar amounts. This is an important difference with other alkaline or alkaline-earth silicate glasses (see [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]) that usually present a strong preference for [5] Ti with minor amounts of [4] Ti. This corresponds to several structural positions for titanium atoms within the glass structure, network former or either network modifier.…”

Section: Short-range Order Around Titanium Atomsmentioning

confidence: 99%

“…The Ti environment in alumino-silicate glasses has only been studied by Ti K-edge XAS [9,14]. Alkaline-earth alumino-silicate glasses with 5 mol% TiO 2 contain both [4] Ti and [5] Ti ( [5] Ti ∼ 60-75 ± 10% of the total Ti), while in alkali alumino-silicate glasses the presence of Al in the glass causes some [5] Ti to transform into [4] Ti, with a maximum of about 40% of [4] Ti.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Environment of titanium and aluminum in a magnesium alumino-silicate glass

Guignard

Cormier

Montouillout

et al. 2009

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

The structure of the glass 2MgO-2Al 2 O 3 -5SiO 2 -TiO 2 was investigated using neutron diffraction with isotopic substitution. Reverse Monte Carlo (RMC) modeling was used to reproduce experimental structure factors derived from diffraction experiments. The local environment of titanium atoms was determined and it corresponds to an average of 5.4 ± 0.2 oxygen atoms at a mean distance of 1.86 ± 0.02Å. This coordination number agrees with the predominance of fivefold coordination, with the coexistence of four-and sixfold coordination in similar amounts. 27 Al nuclear magnetic resonance (NMR) results revealed that the proportion of highly coordinated aluminum atoms in this titanium-bearing glass was higher than in the titanium-free sample. RMC modeling was used to interpret the structural role of these [5] Al species and we show a trend for preferential bonding between [5] Al and Ti atoms. This favored linkage is important to understand the role of titanium dioxide as a nucleating agent in inorganic glass-ceramics fabrication.

show abstract

Section: Introductionmentioning

confidence: 91%

Section: Short-range Order Around Titanium Atomsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Environment of titanium and aluminum in a magnesium alumino-silicate glass

Guignard

Cormier

Montouillout

et al. 2009

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…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

View full text Add to dashboard Cite

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.

show abstract

“…However, the actual coordination of Ti 4+ is also influenced by a number of factors besides TiO 2 content, including total alkalinity, Al content of the melt, etc. (Romano et al 2000). In the system Na 2 O-SiO 2 -TiO 2 , Henderson & Fleet (1995) noted that [4] Ti 4+ dominates at low TiO 2 concentrations, but above 7.1 wt.% TiO 2 , [5] Ti 4+ is found to dominate instead.…”

Section: Discussionmentioning

confidence: 99%

THE CRYSTAL STRUCTURE OF YOSHIMURAITE, A LAYERED Ba-Mn-Ti SILICOPHOSPHATE, WITH COMMENTS ON FIVE-COORDINATED Ti4+

McDonald

Grice

Chao

2000

The Canadian Mineralogist

View full text Add to dashboard Cite

The crystal structure of yoshimuraite, ideally Ba 2 Mn 2 TiO(Si 2 O 7 )(PO 4 )(OH), has been determined and refined to residuals of R = 3.0% and wR = 4.1% using material from the Taguchi mine, Aichi Prefecture, Honshu, Japan. It is triclinic, P1, with cell parameters a 5.386(1), b 6.999(1), c 14.748(3) Å, ␣ 89.98(1), ␤ 93.62(2), ␥ 95.50(2)%, V 552.3(1) Å 3 , with Z = 2. The mineral is strongly layered on (001), consisting of two quasi-tetrahedral layers composed of TiO 5 polyhedra cross-linked by cornersharing (Si 2 O 7 ) clusters. These layers bound on two sides a layer of closest-packed Mn 6 octahedra, thus forming a composite unit reminiscent of that found in 2:1 phyllosilicates. Such composite units are subsequently linked along [001] via an interlayerlike [Ba 2 (PO 4 )] sheet, the bonding between the two being relatively weak and resulting in the pronounced {001} cleavage observed in the mineral. Yoshimuraite is a member of the BM n heterophyllosilicate polysomatic series [specifically, the BM 0 polysome series], which includes phases such as astrophyllite, bafertisite and seidozerite.Keywords: yoshimuraite, barium manganese titanium silicophosphate hydrate, heterophyllosilicate polysomatic series, Taguchi mine, Japan. SOMMAIRENous avons résolu la structure cristalline de la yoshimuraïte, dont la composition idéale est Ba 2 Mn 2 TiO(Si 2 O 7 )(PO 4 )(OH), jusqu'à un résidu R de 3.0% (wR = 4.1%) en utilisant un échantillon de la mine Taguchi, préfecture d'Aichi, île de Honshu, au Japon. Il s'agit d'un minéral triclinique, P1, dont les paramètres réticulaires sont a 5.386 (1) 650THE CANADIAN MINERALOGIST preponderance of P 5+ over S 6+ in the isolated tetrahedral site. X-RAY CRYSTALLOGRAPHY AND CRYSTAL-STRUCTURE DETERMINATIONFor X-ray-diffraction intensity data, a plate measuring 0.09 ϫ 0.06 ϫ 0.04 mm was selected. Although Watanabe et al. (1961) indicated that the crystals of yoshimuraite examined by them all exhibit what they interpreted to be polysynthetic twinning on {001} (twin law unknown), the crystal used in this present study shows no evidence of such twinning after being studied by optical microscopy and X-ray-precession techniques. Single-crystal X-ray-precession photographs confirm that the mineral is triclinic, with possible space-groups P1 and P1. Intensity data were collected on a fully automated Nicolet R3m four-circle diffractometer. A set of 25 reflections was used to orient the crystal and to refine the cell dimensions. Intensity data were collected out to 2 = 60° using the :2 scan mode and a scan range of 2°. A variable scan-rate inversely proportional to the peak intensity was used, with maximum and minimum scan-rates of 29.3° 2/min and 4.0° 2/min, respectively. Data pertinent to the collection of the intensity data are given in Table 2.The data were subsequently corrected for Lorentz, polarization, background effects and absorption and reduced to structure factors using the SHELXTL PC (Sheldrick 1990) package of computer programs. For the ellipsoidal absorption correction, eleve...

show abstract

Effect of aluminum on Ti-coordination in silicate glasses: A XANES study

Cited by 58 publications

References 62 publications

Environment of titanium and aluminum in a magnesium alumino-silicate glass

Environment of titanium and aluminum in a magnesium alumino-silicate glass

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

THE CRYSTAL STRUCTURE OF YOSHIMURAITE, A LAYERED Ba-Mn-Ti SILICOPHOSPHATE, WITH COMMENTS ON FIVE-COORDINATED Ti4+

Contact Info

Product

Resources

About