Self-diffusion of iron and sulfur in ferrous sulfide

Condit, R.H.; Hobbins, R.R.; Birchenall, C. E.

doi:10.1007/bf00603390

Cited by 129 publications

(101 citation statements)

References 44 publications

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“…Similar results have also been observed in the oxidation-sulphidation of Fe-Al alloys [16]. The growth of the outer layer of FeS is dominated by the outward diffusion of Fe, for the outward diffusion rate of Fe through FeS is orders of magnitude larger than the inward diffusion rate of S [17]. Beneath the FeS layer, mixtures of FeCr2O4, Fe2SiO4 and FeS are observed, indicating that oxygen could diffuse through the FeS layer and react with the alloy.…”

Section: Corrosion Behavior Of the As-cast Fe-5cr-5si Alloysupporting

confidence: 81%

The corrosion behavior of a sputtered micrograin film on Fe-5Cr-5Si alloy in H 2 -CO 2 -H 2 S mixture at 700 °C

Liu

Guo

et al. 2016

Corrosion Science

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Section: Corrosion Behavior Of the As-cast Fe-5cr-5si Alloysupporting

confidence: 81%

The corrosion behavior of a sputtered micrograin film on Fe-5Cr-5Si alloy in H 2 -CO 2 -H 2 S mixture at 700 °C

Liu

Guo

et al. 2016

Corrosion Science

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“…While there is as yet no diffusion data for Pb in either silicate or sulfide phases, there is data for Fe and Os that suggests very rapid diffusion rates in mono-sulfide phases. Self-diffusion of Fe in pyrrhotite (Fe 1-x S) at 1400 °C is 5x10 -6 cm 2 /s; in FeS melt, Fe is > 100 times faster (Condit et al 1974;Yang et al 1959). For contrast, Fe 2+ diffusion in basaltic melt is ~ 10x slower than Fe in pyrrhotite!…”

Section: Iiid Transport Of Pb By Diffusion Through Sulfidesmentioning

confidence: 99%

Mantle Pb paradoxes: the sulfide solution

Hart

Gaetani

2006

Contrib Mineral Petrol

115

108

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There is growing evidence that the budget of Pb in mantle peridotites is largely contained in sulfide, and that Pb partitions strongly into sulfide relative to silicate melt. In addition, there is evidence to suggest that diffusion rates of Pb in sulfide (solid or melt) are very fast. Given the possibility that sulfide melt 'wets' sub-solidus mantle silicates, and has very low viscosity, the implications for Pb behavior during mantle melting are profound. There is only sparse experimental data relating to Pb partitioning between sulfide and silicate, and no data on Pb diffusion rates in sulfides. A full understanding of Pb behavior in sulfide may hold the key to several long-standing and important Pb paradoxes and enigmas. The classical Pb isotope paradox arises from the fact that all known mantle reservoirs lie to the right of the Geochron, with no consensus as to the identity of the "balancing" reservoir. We propose that long-term segregation of sulfide (containing Pb) to the core may resolve this paradox.Another Pb paradox arises from the fact that the Ce/Pb ratio of both OIB and MORB is greater than bulk earth, and constant at a value of 25. The constancy of this "canonical ratio" implies similar partition coefficients for Ce and Pb during magmatic processes (Hofmann et al. 1986), whereas most experimental studies show that Pb is more incompatible in silicates than Ce. Retention of Pb in residual mantle sulfide during melting has the potential to bring the bulk partitioning of Ce into equality with Pb if the sulfide melt/silicate melt partition coefficient for Pb has a value of ~ 14. Modeling shows that the Ce/Pb (or Nd/Pb) of such melts will still accurately reflect that of the source, thus enforcing the paradox that OIB and MORB mantles have markedly higher Ce/Pb (and Nd/Pb) than the bulk silicate earth. This implies large deficiencies of Pb in the mantle sources for these basalts. Sulfide may play other important roles during magmagenesis: 1). advective/diffusive sulfide networks may form potent metasomatic agents (in both introducing and obliterating Pb isotopic heterogeneities in the mantle); 2). silicate melt networks may easily exchange Pb with ambient mantle sulfides (by diffusion or assimilation), thus 'sampling' Pb in isotopically heterogeneous mantle domains differently from the silicate-controlled isotope tracer systems (Sr, Nd, Hf), with an apparent 'de-coupling' of these systems.

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“…This experimentally found energy (59 ± 7 kJ mol -1 ) correlates very well with literature reports of vacancy diffusion of iron in iron sulfides. [245,247] This not only confirms that the literature diffusion coefficients are applicable for this system, but also that iron diffusion is the dominant process, further proof that the hollow nanowires are formed by unequal diffusion of iron and the Kirkendall Effect. To quantitatively describe the injection/absorption processes and time-scales, the change in optical density (ΔOD) is analyzed at individual probe wavelengths.…”

Section: Exposure Of Mos2 Nanowires To Reducing Agentssupporting

confidence: 76%

“…At 300°C (the reactor conditions), the average diffusion coefficient of iron cations in Fe1-xSx was measured to be on the order of 9 x 10 -12 cm 2 sec -1 . [245] In these analyses, the diffusion of sulfur in the iron sulfide was assumed to be negligible, due to its diffusion rate being significantly less than iron. In more recent work, sulfur isotopes were used as radiotracers in natural pyrite [246] and experimentally calculated that the diffusion coefficient of sulfur anions in pyrite has a temperature dependence fitting an Arrhenius relationship, given by: 300°C.…”

Section: Exposure Of Mos2 Nanowires To Reducing Agentsmentioning

confidence: 99%

Phase transformation studies of metal oxides to dichalcogenides in 1-d structures.

Cummins¹,

Ray²

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Recently, the use of materials with nanoscale morphologies has expanded, particularly with applications in energy conversion, catalysis, and energy storage. One drawback to single crystalline nanomaterials, especially 1D nanowires, is the difficulty in synthesizing these compounds, as the material chemistry becomes more complicated.Metal oxide nanowires can be synthesized easily and can be produced in relatively large quantities. However, more complex materials, such as metal chalcogenides, cannot typically be synthesized using facile methods, and currently very few techniques involve scalable methods. Phase transformation of metal oxides nanowires to form metal sulfides and selenides by gas-solid reactions is one viable route to scalable chalcogenide production. However, the transformation of 1D materials from oxides to other compositions using gas-solid reactions has not been well studied and the underlying mechanisms involved with phase transformation are minimally understood. A fundamental understanding of how gas phase reactants interact with nanomaterials is critical to not only making new materials on the nanoscale, but also allowing the engineering and optimization of nanomorphologies for functional applications.v Iron sulfide and molybdenum sulfide nanowires are chosen as the two model materials to investigate crystal phase transformations in 1D systems.In reaction of Fe2O3 single crystal nanowires with H2S gas to form FeS, the formation of a hollow nanotube morphology is observed, caused by unequal diffusion of the cation and anion, resulting in the accumulation of voids. These findings suggest that the reactant (sulfur) does not diffuse into the nanostructure; rather, iron atoms diffuse outward and react on the surface. The resulting FeS compound also has interesting optical absorption properties that could be of use in solar applications.The conversion of MoO3 nanowires in an attempt to form MoS2 nanowires resulted in a MoS2/MoOx shell/core nanowire morphology, with strong diffusion limits in formation of the sulfide shell. In this case, the sulfur diffusion through the MoS2 shell limits the reaction, leading to core-shell morphology.The MoS2/MoOx shell/core architecture shows considerable activity for electrocatalysis of the hydrogen evolution reaction due to the high surface area architecture for edge plane sites. Chemical intercalation of the MoS2 shell shows a further change in the crystal morphology and an improvement in catalytic activity. Reducing agents (hydrazine) are also investigated in attempts to chemically modify the MoS2 surface, changing the surface charge carrier concentrations. This is the first report of the effect of hydrazine in any chalcogenide system and the hydrazine treated MoS2 nanowire architecture shows one of the best electrocatalytic performance to date. The chemical modifications of MoS2 1D structures suggest the electrocatalytic activity can be tuned and corresponding architectures could be synthesized through phase transformation by design. These experiments help to d...

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Self-diffusion of iron and sulfur in ferrous sulfide

Cited by 129 publications

References 44 publications

The corrosion behavior of a sputtered micrograin film on Fe-5Cr-5Si alloy in H 2 -CO 2 -H 2 S mixture at 700 °C

The corrosion behavior of a sputtered micrograin film on Fe-5Cr-5Si alloy in H 2 -CO 2 -H 2 S mixture at 700 °C

Mantle Pb paradoxes: the sulfide solution

Phase transformation studies of metal oxides to dichalcogenides in 1-d structures.

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