SiO gas emission and triple line dynamics of small silicon droplets on quartz

Wachsmuth, Dennis; Gebensleben, Tim; Weiss, Daniel H.; Becker, Verena; Alphei, Lukas D.; Becker, J. A.

doi:10.1016/j.jcrysgro.2012.06.044

Cited by 13 publications

(7 citation statements)

References 21 publications

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“…Directed motion is also observed with liquid drops from micrometer to millimeter scales, e.g., with alcanes on glass [9], or Ga/GaAs [10]. In addition, macroscopic reactive liquid droplets such as liquid Si/SiO 2 [4,[11][12][13], or liquid metals on ceramic systems [14] exhibit complex pinning behavior at the liquid-solidvapor triple line. However, the physical processes at play in nanoparticle reactivity may differ from those of larger-scale objects.…”

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confidence: 97%

Nonequilibrium diffusion of reactive solid islands

et al. 2014

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We report on the observation of the random walk of solid-state silicon islands on SiO 2 substrates during annealing at high temperatures. The mean square displacement (MSD) of the islands exhibits three regimes. At short times, the islands undergo equilibrium diffusion and begin to etch the surface thereby creating ringlike trenches. Then, an unusual size independent diffusionlike behavior is observed with a linear increase of the MSD. This behavior is attributed to a pinning instability of the triple line. Finally, as etching proceeds pits are formed in the substrate, and the MSD saturates as the islands are self-trapped in their own pits. Kinetic Monte Carlo simulations reproduce the main features of the three regimes, and provide a consistent picture of the microscopic reaction mechanisms at play in the experiments.

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confidence: 97%

Nonequilibrium diffusion of reactive solid islands

et al. 2014

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“…The entropy driven formation of gaseous SiO can be observed for silicon in contact with metal oxides with in situ mass spectrometry but requires liquid silicon from larger samples [14]. The calculated temperature for the highest heater setting (Fig.…”

Section: Discussionmentioning

confidence: 96%

Transient light emission from the silicothermic reduction of magnesium oxide with potential for monitoring intermediate compound formation and decay

Gebensleben

Becker

2020

SN Appl. Sci.

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Small silicon samples were brought into contact with magnesium oxide substrate plates and heated under vacuum. At heating temperatures above 1400 K, a transient light emission effect in the Si/MgO interface was observed. The changes in sample brightness are likely caused by a thermal effect. Typically the sample temperature decreases gradually by 40-80 K and is followed by a very fast rise in temperature. The light emission effect may be correlated to the transient formation and decomposition of an inhibiting layer of magnesium silicate and the endothermic formation of gaseous silicon oxide. Tempering a silicon sample on a magnesium oxide plate for several hours produced an etch pit in the substrate material from which the silicon sample split off during the cooling phase. The etch pit was investigated via electron microscopy. EDXS analysis of the finely structured surface of the reaction zone reports a composition of 2/1/5 (Mg/Si/O). A crosssection of the same area reveals a thin layer of reaction products on top of the substrate material.

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“…Silica can dissolve in liquid silicon by means of oxygen atoms diffusion in the melt and the simultaneous emission of SiO gas at the interface between the melted silicon and gas phase. Under reduced pressure and/or at high temperature, SiO gas can be generated at the interface between solid silica and liquid silicon, as revealed by the spreading instability of sessile drops that have been observed by Wachsmuth et al [50]. The oxygen solubility in liquid Si is low.…”

Section: Reactions Involving Liquid Siliconmentioning

confidence: 96%

“…The oxygen solubility in solid Si at 1414 • C is 2.68 × 10 18 atoms/cm 3 [51], which corresponds to an equilibrium distribution coefficient of oxygen between solid and liquid silicon equal to 0.873 [51]. In contrast to its solubility, the oxygen mobility in liquid Si is high (diffusion constant estimated at D = 3.3 × 10 −4 cm 2 s −1 [50]).…”

Section: Reactions Involving Liquid Siliconmentioning

confidence: 99%

Densification of Ceramic Matrix Composite Preforms by Si2N2O Formed by Reaction of Si with SiO2 under High Nitrogen Pressure. Part 1: Materials Synthesis

2021

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Ceramic matrix composites (CMCs) have been designed and developed for extreme operating environments. The aim of the present study is to look for a rapid densification process providing a high level of material performance. The fibrous preform was made of Hi-Nicalon S fibers woven in a 3D interlock weave. The matrix was composed of Si2N2O prepared inside the CMCs by reacting a mixture of Si and SiO2 under high nitrogen pressure (1 to 3 MPa). Silica was either impregnated by slurry or obtained by oxidation of silicon grains inside the preform. The synthesis reaction was initiated by heating the impregnated preform by means of a carbon resistor submitted to Joule effect. Composition, homogeneity and porosity of the formed matrix were studied and interpreted as a function of the experimental parameters (nitrogen pressure, heating rate of the preform) as well as the recorded thermal history of the process. The present results show that the matrix formation is almost completed in less than one minute. Melting of silicon has a major influence on the process. Competition was observed between the formation of Si3N4 and Si2N2O, which could be mainly controlled by the heating rate of the preform and the nitrogen partial pressure.

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SiO gas emission and triple line dynamics of small silicon droplets on quartz

Cited by 13 publications

References 21 publications

Nonequilibrium diffusion of reactive solid islands

Nonequilibrium diffusion of reactive solid islands

Transient light emission from the silicothermic reduction of magnesium oxide with potential for monitoring intermediate compound formation and decay

Densification of Ceramic Matrix Composite Preforms by Si2N2O Formed by Reaction of Si with SiO2 under High Nitrogen Pressure. Part 1: Materials Synthesis

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