Vibrational spectroscopy of silicate liquids and glasses

McMillan, Paul F.; Wolf, George H.; Poe, Brent T.

doi:10.1016/0009-2541(92)90064-c

Cited by 232 publications

(164 citation statements)

References 34 publications

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“…The high-frequency region comprises that of the fundamental O-H vibrations in OH groups, whether in molecular H 2 O or as OH groups that form bonding with metal cations (Ratcliffe and Irish 1982;Walrafen et al 1986). The low-frequency region, between about 300 and 1200 cm −1 , includes the Raman bands assigned to vibrations in Si-O, Al-O, and metal oxide components (Brawer and White 1975;McMillan et al 1992).…”

Section: Resultsmentioning

confidence: 99%

Silicate solution, cation properties, and mass transfer by aqueous fluid in the Earth’s interior

Mysen

2018

Prog Earth Planet Sci

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Aqueous fluids in the Earth's interior are multicomponent systems with silicate solubility and solution mechanisms strongly dependent on other dissolved components. Here, solution mechanisms that describe the interaction between dissolved silicate and other solutes were determined experimentally to 825°C and above 1 GPa with in situ vibrational spectroscopy of aqueous fluid while these were at high temperature and pressure. The silicate content in Na-bearing, silicate-saturated aqueous fluid exceeds that in pure SiO 2 at high temperature and pressure. Silicate species were of Q 0 (isolated SiO 4 tetrahedra) and Q 1 (dimers, Si 2 O 7 ) type. The temperature dependence of its equilibrium constant, K = X Q1 /(X Qo ) 2 , yields enthalpies of 22 ± 12 and 51 ± 17 kJ/mol for the SiO 2 -H 2 O and Na-bearing fluids. In contrast, in Ca-bearing fluids, the solubility is more than an order of magnitude lower, and only Q 0 species are present. The present data together with other published experimental information lead to the conclusion that the silicate solubility in aqueous fluids in equilibrium with mafic rocks such as amphibolite and peridotite is an order of magnitude lower than the solubility in fluids in equilibrium with felsic rocks such as andesite and rhyolite compositions (felsic gneiss) under similar temperature and pressure conditions. The silicate speciation also is more polymerized in the felsic systems. This difference is also why second critical end-points in the Earth are at lower temperature and pressure in felsic compared with mafic systems. Alkali-rich fluids formed by dehydration of felsic rocks also show enhanced high field strength element (HFSE) solubility because alkalis in such solution form oxy complexes with the HFSE cations. Fluids formed by dehydration of felsic rocks in the Earth's interior are, therefore, more efficient transport agents of silicate materials than fluids formed by dehydration of mafic and ultramafic rocks, whether for major, minor, or trace elements.

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Section: Resultsmentioning

confidence: 99%

Silicate solution, cation properties, and mass transfer by aqueous fluid in the Earth’s interior

Mysen

2018

Prog Earth Planet Sci

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“…5). A band near 1150 cm À1 is commonly assigned to SiAO stretching in fully polymerized Q 4 structural units (McMillan et al, 1982;Seifert et al, 1982;Matson et al, 1986;McMillan and Wolf, 1995;Neuville and Mysen, 1996). A band near 450 cm À1 is assigned to SiAO rocking motion in fully polymerized Q 4 units (McMillan et al, 1982;McMillan and Wolf, 1995).…”

Section: Raman Spectroscopymentioning

confidence: 99%

Solution behavior of reduced COH volatiles in silicate melts at high pressure and temperature

Mysen

Fogel

Morrill

et al. 2009

Geochimica et Cosmochimica Acta

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The solubility and solution mechanisms of reduced CAOAH volatiles in Na 2 OASiO 2 melts in equilibrium with a (H 2 + CH 4 ) fluid at the hydrogen fugacity defined by the iron-wü stite + H 2 O buffer [f H2 (IW)] have been determined as a function of pressure (1-2.5 GPa) and silicate melt polymerization (NBO/Si: nonbridging oxygen per silicon) at 1400°C. The solubility, calculated as CH 4 , increases from $0.2 wt% to $0.5 wt% in the melt NBO/Si-range $0.4 to $1.0. The solubility is not significantly pressure-dependent, probably because f H2 (IW) in the 1-2.5 GPa range does not vary greatly with pressure. Carbon isotope fractionation between methane-saturated melts and (H 2 + CH 4 ) fluid varied by $14& in the NBO/Si-range of these melts. The (C..H) and (O..H) speciation in the quenched melts was determined with Raman and 1 H MAS NMR spectroscopy. The dominant (C..H)-bearing complexes are molecular methane, CH 4 , and a complex or functional group that includes entities with C"CAH bonding. Minor abundance of complexes that include SiAOACH 3 bonding is tentatively identified in some melts. There is no spectroscopic evidence for SiAC or SiACH 3 . Raman spectra indicate silicate melt depolymerization (increasing NBO/Si). The [CH 4 /C"CAH] melt abundance ratio is positively correlated with NBO/Si, which is interpreted to suggest that the (C"CAH)-containing structural entity is bonded to the silicate melt network structure via its nonbridging oxygen. The $14& carbon isotope fractionation change between fluid and melt is because of the speciation changes of carbon in the melt.

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“…Direct structural studies of Al 2 O 3 -SiO 2 melts and glasses have been carried out (cf. Morikawa et al 1982, Brown et al 1995and references therein, Stebbins 1995, McMillan & Wolf 1995. Morikawa et al (1982) carried out an X-ray-scattering study of a number of compositions along the join Al 2 O 3 -SiO 2 .…”

Section: Aluminum (Al 3+ )mentioning

confidence: 99%

The Structure of Silicate Melts: A Glass Perspective

Henderson

2005

The Canadian Mineralogist

126

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Glasses are widely used as analogues for the study of silicate melts. Although they are solid materials, their structure is inherently complex and diffi cult to study. However, progress has been made in elucidating this structure, its relationship to composition, and how it behaves at high temperatures and pressures. Recent research has brought to light some new fi ndings with important implications for natural melts. These include the observation that the structure is dependent upon the type and size of alkali or alkaline-earth cations incorporated into the glass network, with Li behaving very differently than other alkali cations. In addition, the presence of more than one type of alkali cation can cause non-linear physical behavior. Elements such as Al, Ti and Fe, which play important roles in petrological phenomena, can exhibit coordination environments (e.g., 5-fold) or polyhedral arrangements (e.g., triclusters) that are not common in crystalline phases. Furthermore, polyamorphic phase-transitions may occur at high temperature and pressures; the application of new theoretical models like mean fi eld-constraint hypothesis suggests that several glass phenomena, and probably melt phenomena as well, may be related to stress-rigid to fl oppy transitions. The state of understanding of glass structure, although still rudimentary relative to crystalline materials, has grown exponentially over the last few decades, often with geological researchers at the forefront.Keywords: melts, structure, glasses, petrology, spectroscopy, behavior, model. SOMMAIREOn se sert couramment des verres pour étudier les bains fondus silicatés. Quoiqu'ils sont des matériaux solides, leur structure est naturellement complexe et diffi cile à étudier. Toutefois, des progrès ont été faits dans l'étude de cette structure, sa relation à la composition, et son comportement à températures et pressions élevées. Les projets de recherche récents font ressortir les implications importantes aux bains fondus naturels. A titre d'exemple, la structure dépendrait de la sorte et la taille d'ion alcalin ou alcalino-terreux qui se trouve incorporé dans le réseau du verre. Le Li se comporte de façon très différente des autres alcalins. De plus, la présence de plus d'une sorte d'alcalin peut causer des comportements physiques non-linéaires. Les élements tels Al, Ti et Fe, dont l'importance pétrologique est évidente, peuvent adopter une coordinence inhabituelle, cinq par exemple, et un arrangement polyédrique, des groupements par trois, par exemple, qui ne sont pas communs dans les phases cristallines. De plus, des transitions de phases polyamorphiques pourraient avoir lieu à températures et à pressions élevées. L'application de nouveaux modèles théoriques, par exemple le modèle de contrainte moyenne du champ, fait penser que plusieurs phénomènes impliquant les verres, et tout probablement les bains fondus, pourraient résulter de transitions de matériau rigide face aux contraintes à maté-riau déformable. Quoique les connaissances de la structure du ve...

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Vibrational spectroscopy of silicate liquids and glasses

Cited by 232 publications

References 34 publications

Silicate solution, cation properties, and mass transfer by aqueous fluid in the Earth’s interior

Silicate solution, cation properties, and mass transfer by aqueous fluid in the Earth’s interior

Solution behavior of reduced COH volatiles in silicate melts at high pressure and temperature

The Structure of Silicate Melts: A Glass Perspective

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