Mechanical Properties of Amorphous Silicon Carbide

Xue, Kun; Niu, Li‐Sha; Shi, Hui‐Ji

doi:10.5772/21689

Cited by 8 publications

(5 citation statements)

References 42 publications

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“…Our computational results for unrelaxed a-Si are reported in Table along with experimental data for relaxed a-Si to validate this statement. Beyond that, our ReaxFF-MD calculations predict the Young’s modulus of a-SiC in close agreement with empirical models , fitted from experimental data to our model’s density. Unfortunately, ReaxFF underestimates the high stiffness of 3C-SiC (bulk, shear, and Young’s moduli are 215, 188, and 436 GPa, respectively) compared with experiments published by Thakore et al and previous DFT studies .…”

Section: Resultssupporting

confidence: 73%

Development and Validation of a ReaxFF Reactive Force Field for Modeling Silicon–Carbon Composite Anode Materials in Lithium-Ion Batteries

et al. 2023

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Silicon–carbon (Si–C) nanocomposites have recently established themselves among the most promising next-generation anode materials for lithium (Li)-ion batteries. Indeed, combined Si and graphitic (sp2-C) phases exhibit high energy densities with reasonable electrochemical responses, while covalently bonded silicon carbide (SiC) compounds offer high mechanical stiffness to withstand structural degradation. However, to form and utilize a Si–C composite structure that effectively satisfies specific battery energy, power, and lifetime requirements, it is necessary to understand the underlying atomistic mechanisms at work within its individual phases and at their interfaces. Here, we develop and validate a reactive interatomic potential (ReaxFF) for the Li–Si–C system, trained and tested against a large, diverse collection of ab initio data. In conjunction with molecular dynamics and Monte Carlo simulations, our new force field links macroscale phenomena to the nanostructures of various hybrid Si–C systems in a wide range of lithiation, temperature, and stress conditions. As an illustration, it demonstrates that the high capacity of SiC (5882 mA h g–1) is caused by amorphous lithium carbides (e.g., a-Li4.4C), which soften the overall a-Li4.4(SiC)0.5 system while swelling it volumetrically up to 668%. Furthermore, our force field accurately depicts step-wise lithiation mechanisms and volume changes in Si–sp2-C composites throughout the lithiation domain of each host subsystem. It reveals the formation of a Li-rich interphase at their grain boundary, which favors their adhesion and increases the local Li (de)insertion voltage up to 1 V. These examples demonstrate the ability of the new Li–Si–C ReaxFF potential to provide atomistic-scale insights required for designing and optimizing a wide range of Si–C-based anode candidates for upcoming Li-ion battery technologies.

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Section: Resultssupporting

confidence: 73%

Development and Validation of a ReaxFF Reactive Force Field for Modeling Silicon–Carbon Composite Anode Materials in Lithium-Ion Batteries

et al. 2023

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“…This can be explained as the result of preferential removing of the corroded low crystalline SiC and exposing the carbon phase that existed in the composite before the corrosion, as in the previous case of crystalline SiC. As shown by Xue et al, C‐C bonds and Si‐Si bonds were formed when SiC was a low crystal structure 28,29 . The composite infiltrated at the highest temperature of 1100°C showed little change in the SiC peak, and no additional graphitic carbon was observed (Figure 7C).…”

Section: Resultsmentioning

confidence: 60%

Influence of crystallinity on the corrosion rate of chemically vapor‐infiltrated SiC_f/SiC composites under 310°C hydrothermal condition

Han

Kim

Lee

et al. 2021

Int J Applied Ceramic Tech

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The rationale of this work was to investigate the effect of crystallinity on corrosion rate of chemically vapor‐infiltrated (CVI) SiCf/SiC composites. SiCf/SiC composites were fabricated from fabric preform with densifying by CVI. To evaluate the effect of crystallinity on the behavior of SiCf/SiC composite, the infiltration temperature was increased from 1000 to 1100°C with 25°C intervals. X‐ray diffraction and Raman spectroscopy results indicated the diffraction peaks, as the infiltration temperature elevated, become sharp and the transverse optical (TO) and longitudinal optical (LO) phonon peak of the composite increased, respectively. Hydrothermal corrosion tests were performed on the polished surface in a static autoclave at a DI water for 7 and 30 days to evaluate the relation of crystallinity and the microstructure of the composite. Low infiltration temperature revealed columnar growth structure at the matrix after corrosion while weight loss behavior had a linear decreasing tendency from 1000 to 1075°C. These findings are particularly important for determining the infiltration temperature which changes the crystallinity of the SiC phase, and hence the corrosion rate of SiCf/SiC composites.

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“…Electron energy loss microscopy (EELS) measurements reveal that the underlying mechanism is stress gradient induced. Understanding the prefracture deformation stage of a-Si, a typical covalently bonded amorphous material which is intrinsically brittle at room temperature, , will provide insights into the atomic structure reconfigurations of covalent amorphous materials.…”

Section: Resultsmentioning

confidence: 99%

Tunable Anelasticity in Amorphous Si Nanowires

Wang

Liang

et al. 2019

Nano Lett.

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In situ bending tests of amorphous Si nanowires (a-Si NWs) found different elastic behavior depending on whether they were straight or curved to begin with. The axially straight NWs exhibit pure elastic deformation; however, the axially curved NWs exhibit obvious anelastic behavior when they are bent in the direction of original curvature. On the basis of STEM-EELS analysis, we propose that the underlying mechanism for this anelastic behavior is a bond-switching assisted redistribution of the nonuniform density (structure) in the curved NWs under the inhomogeneous stress field. This mechanism was further supported by the fact that the originally straight a-Si NWs also display similar anelasticity with the as-grown curved NWs after focused ion beam irradiation that can cause nonuniform structure distribution. As compared to what has been reported in other 1D materials, the anelasticity of a-Si NWs can be tuned by modifying their morphology, controlling the loading direction, or irradiating them via ion beam. Our findings suggest that a-Si NWs could be a promising material in the nanoscale damping systems, especially the semiconductor nanodevices.

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Mechanical Properties of Amorphous Silicon Carbide

Cited by 8 publications

References 42 publications

Development and Validation of a ReaxFF Reactive Force Field for Modeling Silicon–Carbon Composite Anode Materials in Lithium-Ion Batteries

Development and Validation of a ReaxFF Reactive Force Field for Modeling Silicon–Carbon Composite Anode Materials in Lithium-Ion Batteries

Influence of crystallinity on the corrosion rate of chemically vapor‐infiltrated SiC_f/SiC composites under 310°C hydrothermal condition

Tunable Anelasticity in Amorphous Si Nanowires

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Mechanical Properties of Amorphous Silicon Carbide

Cited by 8 publications

References 42 publications

Development and Validation of a ReaxFF Reactive Force Field for Modeling Silicon–Carbon Composite Anode Materials in Lithium-Ion Batteries

Development and Validation of a ReaxFF Reactive Force Field for Modeling Silicon–Carbon Composite Anode Materials in Lithium-Ion Batteries

Influence of crystallinity on the corrosion rate of chemically vapor‐infiltrated SiCf/SiC composites under 310°C hydrothermal condition

Tunable Anelasticity in Amorphous Si Nanowires

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Influence of crystallinity on the corrosion rate of chemically vapor‐infiltrated SiC_f/SiC composites under 310°C hydrothermal condition