Characterization of laser synthesized silicon nitride powders with nanoscale by solid-state NMR

Yue, Yong; Dao-huo, LI; Ye, Chaohui

doi:10.1007/bf00274913

Cited by 3 publications

(3 citation statements)

References 9 publications

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“…Overall, our results agree well with experimentally measured 29 Si NMR spectra of amorphous Si 3 N 4 or Si 3 N 4 nanopowders, which feature a broad peak centered at −46 to −49 ppm with FWHM of around 25 ppm and distorted towards lower δ iso values [ 5 , 49 , 50 ]. We find that the asymmetry can be related to Si [4] sites with a fifth N atom in proximity closer than 2.8 Å.…”

Section: Resultssupporting

confidence: 89%

“…In recent years, DFT calculations have become an indispensable tool enhancing the analytical strength of experimental NMR studies of glasses and amorphous materials [ 8 , 9 , 10 , 13 , 40 , 48 ]. Several experimental 29 Si NMR studies of amorphous silicon nitride, Si 3 N 4 , have been reported [ 5 , 49 , 50 ]. They show a typical broad “peak” located at δ iso ≈ −46 to −49 ppm.…”

Section: Resultsmentioning

confidence: 99%

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29Si NMR Chemical Shifts in Crystalline and Amorphous Silicon Nitrides

Ponomarev

Kroll

2018

Materials

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We investigate 29Si nuclear magnetic resonance (NMR) chemical shifts, δiso, of silicon nitride. Our goal is to relate the local structure to the NMR signal and, thus, provide the means to extract more information from the experimental 29Si NMR spectra in this family of compounds. We apply structural modeling and the gauge-included projector augmented wave (GIPAW) method within density functional theory (DFT) calculations. Our models comprise known and hypothetical crystalline Si3N4, as well as amorphous Si3N4 structures. We find good agreement with available experimental 29Si NMR data for tetrahedral Si[4] and octahedral Si[6] in crystalline Si3N4, predict the chemical shift of a trigonal-bipyramidal Si[5] to be about −120 ppm, and quantify the impact of Si-N bond lengths on 29Si δiso. We show through computations that experimental 29Si NMR data indicates that silicon dicarbodiimide, Si(NCN)2 exhibits bent Si-N-C units with angles of about 143° in its structure. A detailed investigation of amorphous silicon nitride shows that an observed peak asymmetry relates to the proximity of a fifth N neighbor in non-bonding distance between 2.5 and 2.8 Å to Si. We reveal the impact of both Si-N(H)-Si bond angle and Si-N bond length on 29Si δiso in hydrogenated silicon nitride structure, silicon diimide Si(NH)2.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

29Si NMR Chemical Shifts in Crystalline and Amorphous Silicon Nitrides

Ponomarev

Kroll

2018

Materials

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“…The latter is of particular importance, since the fracture toughness of a fibrous composite depends largely on the fiber pull-out process during failure. 18 In the past, we had reported on the development of a novel nanoindenter assisted technique that could be used for performing in situ nanomechanical testing on 1D nanomaterials. 19,20 We also reported on the usage of the technique to perform 15 successful single fiber pullout experiments, which allowed us to measure the fracture energy, G c , of the pristine multi-walled carbon nanotube (MWNT)-Epon 828 interface.…”

Section: Introductionmentioning

confidence: 99%

Fracture toughness of the sidewall fluorinated carbon nanotube-epoxy interface

Ganesan

Salahshoor

Cheng

et al. 2014

Journal of Applied Physics

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The effects of carbon nanotube (CNT) sidewall fluorination on the interface toughness of the CNT epoxy interface have been comprehensively investigated. Nanoscale quantitative single-CNT pull-out experiments have been conducted on individual fluorinated CNTs embedded in an epoxy matrix, in situ, within a scanning electron microscope (SEM) using an InSEM® nanoindenter assisted micro-device. Equations that were derived using a continuum fracture mechanics model have been applied to compute the interfacial fracture energy values for the system. The interfacial fracture energy values have also been independently computed by modeling the fluorinated graphene-epoxy interface using molecular dynamics simulations and adhesion mechanisms have been proposed.

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29Si NMR

2002

Pergamon Materials Series

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Characterization of laser synthesized silicon nitride powders with nanoscale by solid-state NMR

Cited by 3 publications

References 9 publications

29Si NMR Chemical Shifts in Crystalline and Amorphous Silicon Nitrides

29Si NMR Chemical Shifts in Crystalline and Amorphous Silicon Nitrides

Fracture toughness of the sidewall fluorinated carbon nanotube-epoxy interface

29Si NMR

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