Effects of strong network modifiers on Fe3+/Fe2+ in silicate melts: an experimental study

Борисов, А. А.; Behrens, Harald; Holtz, François

doi:10.1007/s00410-017-1337-1

Cited by 27 publications

(8 citation statements)

References 46 publications

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“…This was documented previously in synthetic and natural glasses (e.g. Carmichael, 1988, 1991;Lange and Carmichael, 1989;Moretti, 2005;Borisov et al, 2017). Again, for the samples KS4, NS4 and CMS prepared in reducing conditions of ~IW, no measurable amount of ferric iron could be detected in the Mössbauer spectra.…”

Section: Reassessment Of Redox Ratios Based On Conventional Mössbauer...supporting

confidence: 84%

Structural, redox and isotopic behaviors of iron in geological silicate glasses: A NRIXS study of Lamb-Mössbauer factors and force constants

Roskosz¹,

Dauphas

et al. 2022

Geochimica et Cosmochimica Acta

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Section: Reassessment Of Redox Ratios Based On Conventional Mössbauer...supporting

confidence: 84%

Structural, redox and isotopic behaviors of iron in geological silicate glasses: A NRIXS study of Lamb-Mössbauer factors and force constants

Roskosz¹,

Dauphas

et al. 2022

Geochimica et Cosmochimica Acta

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“…Although ferrous and ferric iron in basaltic glasses have co-ordination numbers close to V (though this may be through a combination of IV-and VI-fold rather than V-fold itself), ferric iron tends to be in slightly lower co-ordination environments than does ferrous iron (Wilke et al 2007;Knipping et al 2015). In both cases, the addition of alkalis stabilises tetrahedrally co-ordinated iron, the effect being more pronounced for Fe 3+ (Jackson et al 2005b;Knipping et al 2015;Borisov et al 2017), again inversely proportional to their bond valence (Rb + > K + > Na + > Li + ). The relative compressibility of oxide components in silicate melts leads to structural changes as a function of pressure (e.g., Kress and Carmichael 1991) that can affect isotopic fractionation (section 2.0).…”

Section: Meltsmentioning

confidence: 99%

“…Dickenson and Hess (1986) show that 𝛾𝐹𝑒𝑂 𝛾𝐹𝑒𝑂 1.5 potassium stabilises tetrahedrally-co-ordinated ferric iron by charge balance. Recent work by Borisov et al (2017) illustrates that this stabilisation occurs inversely proportional to their bond valence in silicate melts (e.g. Farges et al 2004) whereas Al competes with Fe 3+ for tetrahedral sites.…”

Section: Meltsmentioning

confidence: 99%

The Role of Redox Processes in Determining the Iron Isotope Compositions of Minerals, Melts, and Fluids

Sossi¹,

Debret²

2021

Magma Redox Geochemistry

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Stable isotope fractionation is a response to the minimisation of free energy associated with differences in vibrational frequencies during substitution of isotopic masses between two phases. Site properties are dictated by the bonding environment of iron, and influence its 'force constant', a descriptor for bond strength. Because iron readily transitions between its ferrous (Fe 2+ ) and ferric (Fe 3+ ) state over the oxygen fugacities (fO 2 ) of terrestrial magmas, redox processes are presumed to control iron isotope fractionation. In fact, both co-ordination and redox state are key to interpreting iron isotope variations in high-temperature, high-pressure geological systems. Determinations of iron force constants by experimental, theoretical and spectroscopic means in minerals, melts and fluids are reviewed, emphasising the effect of composition in influencing isotopic fractionation. Within this framework, the application of numerical models of partial melting to iron isotope variations in oceanic basalts and subduction-zone (or arc) magmas has shed light on their genesis. The influence of melt composition, mineral mode and fluid exsolution in producing iron isotope fractionation in evolving magmas is explored. Iron isotopic signatures in magmatic rocks are linked to that of their sources, and are influenced by the iron isotopic evolution of subducting slabs and transfer of fluids to the mantle wedge. 2.0. Principles and nomenclature Ratios of two isotopes, n and d of an element, E, are generally expressed relative to their ratio in a standard in delta notation, which is given by:(1) 𝛿 𝑛/𝑑 𝐸 = ( ( 𝑛 𝐸/ 𝑑 𝐸) 𝑠𝑎𝑚𝑝𝑙𝑒

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“…It thus prevented the full development of the oxide scale layer by inhibiting reaction –reaction . However, M 2+ (Fe 2+ and Mn 2+ ) are recognized as the network modifiers that can shorten the chain length of the melt network and cause a drop in viscosity . The drop in viscosity in the melt can create a pathway for fast diffusion of oxygen into the melt, which consequently accelerates the formation of O 2– through reaction .…”

Section: Resultsmentioning

confidence: 99%

“…However, M 2+ (Fe 2+ and Mn 2+ ) are recognized as the network modifiers that can shorten the chain length of the melt network and cause a drop in viscosity. 26 The drop in viscosity in the melt can create a pathway for fast diffusion of oxygen into the melt, 27 which consequently accelerates the formation of O 2− through reaction 2. This individual charge then reacted with M 2+ and M 3+ in the melt to cause the nucleation of oxide particles (Figure 2a,b).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Intrinsic Effect of Alkali Concentration on Oxidation Reactivity and High-Temperature Lubricity of Silicate Melts between Rubbed Steel/Steel Contacts

et al. 2020

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The present study investigated oxidation reactivity and hot lubricity of a sodium silicate melt at different Na 2 O/SiO 2 ratios under elevated temperature stimulation. Static oxidation prevention was achieved at 920 °C when the Na 2 O/SiO 2 ratio reached 1:3 (trisilicate) and 1:2 (disilicate), but it started to deteriorate in the case of 1:1 (metasilicate). At a high concentration of sodium (metasilicate), a severe corrosion reaction between the melt and oxide took place that resulted in a composite coating on the steel substrate. This high-temperature reaction accelerated the formation of ionic charges from the steel base and promoted oxidation. However, friction and wear reduction is proportional to an increase in the sodium oxide fraction. Metasilicate (1:1) exhibited excellent lubricity under the hot frictional test at 920 °C compared to other lubricants. It was due to the formation of the sodium-saturated surfaces and an amorphous silica layer, which was associated with the high-temperature reactivity of sodium toward the oxide surface. In addition, the NaFeO 2 −Fe 2 O 3 composite film, as the reaction product of individual sodium charge and oxide, plays a significant role in maintaining the tribofilm stability for metasilicate, which was not present for disilicate. This study advances the understanding of how sodium-containing compounds perform oxidation prevention and generate lubricity at hot rubbed surfaces.

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Effects of strong network modifiers on Fe3+/Fe2+ in silicate melts: an experimental study

Cited by 27 publications

References 46 publications

Structural, redox and isotopic behaviors of iron in geological silicate glasses: A NRIXS study of Lamb-Mössbauer factors and force constants

Structural, redox and isotopic behaviors of iron in geological silicate glasses: A NRIXS study of Lamb-Mössbauer factors and force constants

The Role of Redox Processes in Determining the Iron Isotope Compositions of Minerals, Melts, and Fluids

Intrinsic Effect of Alkali Concentration on Oxidation Reactivity and High-Temperature Lubricity of Silicate Melts between Rubbed Steel/Steel Contacts

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