Experimental studies of the vapor phase nucleation of refractory compounds. I. The condensation of SiO

Nuth, Joseph A.; Donn, B.

doi:10.1063/1.444109

Cited by 83 publications

(79 citation statements)

References 15 publications

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“…Maser emission lines confirm the presence of SiO molecules close to such stars, and silicate grains are inferred to be present in their circumstellar shells due to the observation of a broad emission or absorption band around 10 μm and a fainter, broad emission band around 20 μm which are associated with silicate grains (Habing 1996;Danchi et al 1994). SiO has been considered to be a likely candidate for dust nucleation (Nuth & Donn 1982;Gail & Sedlmayr 1986) because it is the most abundant reactive oxygen-bearing species in O-rich circumstellar shells, suggesting that it will be the first species to condense from the gas phase. SiO also has an exceptionally high bond energy such that it is stable even at high temperatures; SiO has been observed to condense at 1000 K under laboratory conditions.…”

Section: Introductionmentioning

confidence: 71%

“…The surface free energy for SiO is not well determined. Nuth & Donn (1982) found values of 500 and 650 erg cm −2 , depending on the method of data analysis, but also cite values ranging from 180 to 850 from the works of other authors. Consequently, we will assume a baseline value of 450 erg cm −2 for the SiO surface free energy σ .…”

Section: Results For a Sample Parameter Setmentioning

confidence: 94%

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A Model of Silicate Grain Nucleation and Growth in Circumstellar Outflows

Paquette

Ferguson

Nuth

2011

ApJ

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Based on its abundance, high bond energy, and recent measurements of its vapor pressure SiO is a natural candidate for dust nucleation in circumstellar outflows around asymptotic giant branch stars. In this paper, we describe a model of the nucleation and growth of silicate dust in such outflows. The sensitivity of the model to varying choices of poorly constrained chemical parameters is explored, and the merits of using scaled rather than classical nucleation theory are briefly considered. An elaboration of the model that includes magnesium and iron as growth species is then presented and discussed. The composition of the bulk of the grains derived from the model is consistent with olivines and pyroxenes, but somewhat metal-rich grains and very small, nearly pure SiO grains are also produced.

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Section: Introductionmentioning

confidence: 71%

Section: Results For a Sample Parameter Setmentioning

confidence: 94%

A Model of Silicate Grain Nucleation and Growth in Circumstellar Outflows

Paquette

Ferguson

Nuth

2011

ApJ

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“…One possibility [6,61] is that melts condensed metastably at lower nebular pressures, but this requires substantial supersaturation of the vapor with respect to the stable solid condensates. High supersaturations have been achieved experimentally [63,64] but they are very specific to the particular systems and experimental conditions studied. The experiments also clearly indicate that there are conditions for which supersaturation would be negligible.…”

Section: Origin Of Type C Inclusions As Liquid Condensatesmentioning

confidence: 99%

The origin of type C inclusions from carbonaceous chondrites

Beckett

Grossman

1988

Earth and Planetary Science Letters

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Type C inclusions are plagioclase-rich, Ca-, Al-rich inclusions found in carbonaceous chondrites. They formed as solid condensates which were later melted in an event that destroyed the original condensate grains. Neither the melting event nor secondary alteration had a significant effect on bulk composition. Two stages in the condensation history can be discerned on the basis of major element bulk compositions. As in type A inclusions, the condensate phase assemblage originally consisted of melilite + spinel + perovskite + hibonite. Type C's were, however, significantly enriched in spinel relative to unaltered portions of most type A's. In contrast to type A's, condensate grains of spinel and melilite in type C's reacted partially with a coexisting gas to produce anorthite + diopside. One-half to two-thirds of the silica now in type C inclusions was introduced by this process. The reactions involving melilite and spinel that are predicted by equilibrium condensation calculations for a cooling gas of solar composition did not occur, probably due to kinetic constraints. Type C's may be related to Al-rich chondrules in ordinary chondrites by the addition of olivine and albite. Bulk compositions of Al-rich chondrules in enstatite chondrites are consistent with the addition of orthopyroxene and albite to type C inclusions. Thus, types A and C inclusions and Al-rich chondrules could represent sequences of condensates removed from interaction with the primitive solar nebula at progressively lower temperatures. If Al-rich chondrules represent the high-temperature component in chondritic material, then type C inclusions rather than the more common subgroups of CAIs could be the true parents of chondrites.

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“…Other possibilities are that both solid SiO 2 and metallic Si are generated through disproportionation reactions of SiO (e.g., Mamiya et al, 2001;Han et al, 2003) and that solid SiO is produced. Though solid SiO is known to be unstable at any temperature and atmospheric pressure (Brewer and Green, 1957), vapor condensates consist of metastable substances under some conditions (e.g., Nuth and Donn, 1982;Rietmeijer et al, 1999). Generation of reduced-state silicon, such as Si 0 , in LPV experiments is also reported although the elemental composition of the reaction system is considerably different from ours; more metallic elements, such as Ca, Mg and Al, are included Gerasimov et al, 1996).…”

Section: The Fate Of Silica That Released Oxygenmentioning

confidence: 88%

Oxidation of carbon compounds by silica-derived oxygen within impact-induced vapor plumes

et al. 2013

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Impact-induced vapor plumes produce a variety of chemical species, which may play an important role in the evolution of planetary surface environments. In most previous theoretical studies on chemical reactions within impact-induced vapor plumes, only volatile components are considered. Chemical reactions between silicates and volatile components have been neglected. In particular, silica (SiO 2 ) is important because it is the dominant component of silicates. Reactions between silica and carbon under static and carbon-rich "metallurgic" conditions (C/SiO 2 1) are known to occur to produce CO and SiC. Actual impact vapor plumes, however, cool dynamically and have carbon-poor "meteoritic" composition (C/SiO 2 1). Reactions under such conditions have not been investigated, and final products in such reaction systems are not known well. Although CO and SiO are thermodynamically stable at high temperatures under carbon-poor conditions, C and SiO 2 are stable at low temperatures. Thus, CO may not be able to survive the rapidly cooling process of vapor plumes. In this study, we conduct laser pulse vaporization (LPV) experiments and thermodynamic calculations to examine whether interactions between carbon and silica occur in rapidly cooling vapor plumes with meteoritic chemical compositions. The experimental results indicate that even in rapidly cooling vapor plumes with meteoritic compounds are rather efficiently oxidized by silica-derived oxygen and that substantial amounts of both CO 2 and CO are produced. The calculation results also suggest that those oxidation reactions seen in LPV experiments might occur in planetary-scale vapor plumes regardless of impact velocity as long as silicates vaporize.

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Experimental studies of the vapor phase nucleation of refractory compounds. I. The condensation of SiO

Abstract: Experimental studies of the vapor phase nucleation of refractory compounds. V. The condensation of lithium

Cited by 83 publications

References 15 publications

A Model of Silicate Grain Nucleation and Growth in Circumstellar Outflows

A Model of Silicate Grain Nucleation and Growth in Circumstellar Outflows

The origin of type C inclusions from carbonaceous chondrites

Oxidation of carbon compounds by silica-derived oxygen within impact-induced vapor plumes

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