Model for evolution of periodic layered structure in the SiO2/Mg system

Gutman, I.; Klinger, L.; Готман, И.; Shapiro, M.

doi:10.1016/j.ssi.2009.08.015

Cited by 23 publications

(23 citation statements)

References 8 publications

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“…Till now, the periodic layered structure has been evidenced in the other systems [16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Not only in the solid state reaction [16][17][18][19][20][21][22][23][24], but also in the solid-liquid reaction [25][26][27][28], even solid-vapor reaction [29]. In this kind of structure, phase layers appears periodically in time and space.…”

Section: Formation Mechanism Of Periodic Layered Structurementioning

confidence: 99%

Formation of periodic layered structure during reaction between Co2Si and liquid Zn

Liu

Tang

Dong

et al. 2016

Surface and Coatings Technology

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Reactions of Co 2 Si alloy with liquid zinc for annealing time up to 720 minutes were studied by means of scanning electron microscope, energy-dispersive X-ray spectroscope and electron backscattered diffraction techniques. The results showed that periodic patterns, Co 2 Si / (γ 2 + η-Zn), were observed in the reaction zone, and its thickness and morphology were dependent on the crystallographic orientation of Co 2 Si grain. The relationship between anisotropy growth of the periodic patterns and crystal structure was explained with the concept of dangling bonds. The thermodynamic foundation and mechanism of formation of the periodic layered structure were elaborated in this paper.

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Section: Formation Mechanism Of Periodic Layered Structurementioning

confidence: 99%

Formation of periodic layered structure during reaction between Co2Si and liquid Zn

Liu

Tang

Dong

et al. 2016

Surface and Coatings Technology

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“…The structure is composed of Mg 2 Si‐rich and MgO‐rich phases with a few micrometers in thickness and periodically arranged parallel to the surface of the silica glass or quartz crystal. Models and mechanisms for forming such periodic structures have been investigated . In these reactions, however, the formation of silicon has not been clearly reported, while a noticeable fact that the nearest neighbor of the unreacted SiO 2 substrates is always the MgO‐rich phase has been described .…”

Section: Introductionmentioning

confidence: 99%

“…Models and mechanisms for forming such periodic structures have been investigated . In these reactions, however, the formation of silicon has not been clearly reported, while a noticeable fact that the nearest neighbor of the unreacted SiO 2 substrates is always the MgO‐rich phase has been described . After the pioneering works, the magnesiothermic reduction of soda‐lime silicate and silica glass substrates with magnesium deposited on the substrates was reported, in which Raman spectra showed that nanocrystalline silicon was successfully prepared .…”

Section: Introductionmentioning

confidence: 99%

“…19,20 The magnesiothermic reduction has also been applied to silica glass substrates and quartz crystals. [21][22][23][24][25][26][27] Gutman et al performed the reduction with magnesium powder via the solid-state reaction at 500-640°C and found that an intriguing structure is generated. [21][22][23] The structure is composed of Mg 2 Si-rich and MgO-rich phases with a few micrometers in thickness and periodically arranged parallel to the surface of the silica glass or quartz crystal.…”

mentioning

confidence: 99%

“…[22][23][24] In these reactions, however, the formation of silicon has not been clearly reported, while a noticeable fact that the nearest neighbor of the unreacted SiO 2 substrates is always the MgO-rich phase has been described. [21][22][23][24] After the pioneering works, the magnesiothermic reduction of soda-lime silicate and silica glass substrates with magnesium deposited on the substrates was reported, in which Raman spectra showed that nanocrystalline silicon was successfully prepared. 25,26 Ma et al 26 mentioned that the thickness of the deposited magnesium is an important factor to obtain the maximal amount of silicon.…”

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Controlled preparation of silicon and magnesium silicide on silica glass substrate through magnesiothermic reduction

Henmi

Shiono

Matsubara

et al. 2020

Int J Ceramic Engine & Sci

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Magnesiothermic reduction has received attention as a method to produce silicon retaining the morphology of the silicon dioxides that serve as the starting materials of the reduction. We performed the reduction of silica glass substrates with magnesium deposited on them under various conditions, including changing the reaction temperature from 500 to 700°C, changing the reaction time from 15 to 420 minutes, and changing the thickness of the deposited magnesium film from 6.6 to 12.1 μm. Crystalline products and their amounts were investigated using X‐ray diffraction. In these reactions, the silica glass substrates were reduced to silicon and/or magnesium silicide depending on the conditions. Under the conditions where the reaction temperature is higher, the reaction time is longer, and the thickness of the magnesium is thinner, silicon was generated more predominantly than magnesium silicide, and vice versa. Under the intermediate conditions, both crystalline silicon and magnesium silicide were generated. Furthermore, it was revealed that the magnesium silicide was rapidly generated within 15 minutes at temperatures higher than 600°C. Then, as the reaction continued, the amount of magnesium silicide gradually decreased, and that of silicon increased. From these results, a two‐step reaction model was proposed: At first, silicon dioxide is reduced to magnesium silicide with the complete consumption of the deposited magnesium; and subsequently, the magnesium silicide reacts with unreacted silicon dioxide and silicon in the intermediate oxidation states to produce silicon. Based on this model, silicon and magnesium silicide were selectively prepared under well‐controlled conditions.

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Mechanisms of Si Nanoparticle Formation by Molten Salt Magnesiothermic Reduction of Silica for Lithium‐ion Battery Anodes

2021

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Molten salt methods enable the synthesis of Si nanostructures by moderating the thermal energy evolved in highly exothermic magnesiothermic reduction reactions (MRR) of silica. Due to their cost‐effectiveness and scalability, these techniques are well suited for producing nanoscale Si for a number of applications, including energy storage. To control the microstructure morphology and particle size, it is necessary to understand the formation mechanism of the Si produced. By evaluating the time‐resolved phase evolution, when NaCl moderates the thermal energy generated by MRR of SiO2, we elucidate 3 parallel interfacial reaction mechanisms yielding Si nanoparticles – via Mg vapor, Mg‐rich eutectic liquid, and Mg ions dissolved in molten NaCl. These individual Si nanoparticles offer a striking contrast to the typical by‐product of MRR of SiO2 with and without NaCl, which yields a 3‐dimensional (3‐D) porous network of sintered Si nanoparticles. Lithium‐ion battery half‐cells with electrodes composed of individual Si nanoparticles showed a greater first‐cycle irreversible discharge capacity and faster capacity loss over the first 5 cycles at a current density of 200 mA g−1 compared to half‐cells with electrodes of a porous 3‐D Si network–indicative due to thicker solid electrolyte interphase (SEI) formation on individual particles. At a higher current rate of 400 mA g−1, once SEI formation and activation of Si are established, both cells exhibit a similar capacity retention rate over 100 cycles.

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Model for evolution of periodic layered structure in the SiO2/Mg system

Cited by 23 publications

References 8 publications

Formation of periodic layered structure during reaction between Co2Si and liquid Zn

Formation of periodic layered structure during reaction between Co2Si and liquid Zn

Controlled preparation of silicon and magnesium silicide on silica glass substrate through magnesiothermic reduction

Mechanisms of Si Nanoparticle Formation by Molten Salt Magnesiothermic Reduction of Silica for Lithium‐ion Battery Anodes

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