Application of Raman microscopy to the analysis of silicon carbide monofilaments

Ward, Yanling; Young, Robert J.; Shatwell, R.A.

doi:10.1023/b:jmsc.0000045606.60263.27

Cited by 80 publications

(54 citation statements)

References 29 publications

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“…[8] An 875-cm À1 peak is located at the middle of SiC zone-centered TO and LO mode [about (TO + LO)/2], which can be attributed to amorphous SiC. [1,7] At the same time, amorphous SiC is observed in SiC grains (Fig. 5), which confirms Raman suggestion.…”

Section: Resultssupporting

confidence: 67%

“…Raman spectroscopy has been applied successfully to characterize SiC crystal polytypes, [4] microstructure of polymeric precursor SiC fiber, [5,6] and CVD SiC fiber. [1,7] During Raman characterization of nano materials, many researchers observed that the Raman features were different from that of bulk material. In bulk materials, only the zone-center (q = 0) optical phonons can be observed by Raman spectroscope.…”

Section: Introductionmentioning

confidence: 99%

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Raman investigation of defective SiC nanocrystals

Zhang

Yang

Ouyang

et al. 2015

J Raman Spectroscopy

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Phonon confinement effect and surface optical mode in SiC nanocrystal have been investigated through Raman spectroscopy. Considering high density of stacking faults in SiC grains, the correlation length of RWL (proposed by Richter, Wang, Li to explain phonon confinement in nano silicon) model is determined as a distance between nearby stacking faults. Thus, homogeneous region becomes thin slices in cylindrical SiC grains, which redefines weighting function. Effect of anisotropy of phonon dispersion curve is also analyzed during calculation. The additional 875-cm À1 band is attributed to defects and amorphous SiC, which is confirmed by transmission electron microscopy. SiC grains are approximated as column array with grain boundary substances regarded as surrounding medium, which explains surface optical phonon mode at 915 cm À1 .

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Section: Resultssupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Raman investigation of defective SiC nanocrystals

Zhang

Yang

Ouyang

et al. 2015

J Raman Spectroscopy

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“…Compared with the buffer and the IPyC layer, Raman spectrum of the OPyC layer exhibits two broad peaks (e.g. D peak and G peak) due to a large amount of defects in the amorphous carbon structure [18]. It is correlated with the reduction of defects in both the buffer and the IPyC layer after annealing at 1560 °C during the SiC deposition process [19].…”

Section: Microstructure Of Triso Particle Layersmentioning

confidence: 99%

“…The texture of PyC layers was analyzed using polarized Raman spectroscopy with two polarization configurations, namely {z (x, x) -z} and {z (y, y) -z}. The definition of the four-letters expression is called Damen's notation [18], in which the symbols outside the parenthesis show the direction of the incident and scattered light and the symbols in parentheses specify mean the polarization direction of the incident and scattered light, respectively. The polarization configurations were controlled by inserting a half-wave plate and polarizer in the beam path between the sample and the spectrometer.…”

Section: Polarized Raman Spectroscopymentioning

confidence: 99%

“…Raman spectrum of SiC shows two first order peaks at around 796 cm -1 (TO peak) and 972 cm -1 (LO peak) with second-order peaks between 1400 cm -1 and 1800 cm -1 , which corresponds to stoichiometry 3C-SiC. A reduction of the symmetry of the LO peak indicates that stacking faults existed within the SiC layer [18], which may influence the fitting accuracy of the peak. Therefore, the TO peak is chosen to determine the thermal conductivity.…”

Section: Microstructure Of Triso Particle Layersmentioning

confidence: 99%

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Evaluation of thermal conductivity of the constituent layers in TRISO particles using Raman spectroscopy

Cao

Liu

Wang

et al. 2017

Journal of the European Ceramic Society

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The thermal conductivity of individual layer in the tristructural-isotropic fuel particle was evaluated using Raman spectroscopy. In this method, laser acted simultaneously as an excitation source and a heating source. A three-dimensional point-heating model was developed to estimate the local temperature rise in the probing volume of the laser. The thermal conductivity can be evaluated based on the dependences of the Raman peak position on the temperature and laser power. The calculated thermal conductivities were 8.9±0.2 W/m·°C, 13.9±1.5 W/m·°C and 11.9±0.9 W/m·°C for the buffer, the inner and the outer PyC layers, respectively. Contrastly, the thermal conductivity of the SiC layer was 4.1 W/m·°C, which is much lower than the reference value, e.g. 168 W/m·°C reported by López-Honorato et al. (J. Nucl. Mater. 378(1) 35-39, 2008). The uncertainty of employing Raman spectroscopy to determine thermal conducitvity was discussed.

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Determination of thermal conductivity using micro‐Raman spectroscopy with a three‐dimensional heating model

Cao

2019

J Raman Spectroscopy

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The thermal conductivity of isotropic graphite was investigated using Raman spectroscopy technique. In this method, the Raman laser acted simultaneously as an excitation source and a heating source. The dependences of the Raman peak position on temperature and laser power for the isotropic graphite were analyzed to establish Raman thermometry. Meanwhile, the local temperature rise induced by the laser irradiation was also theoretically described using a three‐dimensional heating model, which can be related to the thermal conductivity. The laser absorptivity, the spot size, and the probing volume of Raman spectra were discussed, respectively. Besides, simulations of the localized temperature distribution were performed. On the basis of the Raman thermometry and the three‐dimensional heating model, the thermal conductivity of 55 W/m K for the isotropic graphite was estimated, which was comparable with the value (60 W/m K) obtained by the laser flash technique.

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Application of Raman microscopy to the analysis of silicon carbide monofilaments

Cited by 80 publications

References 29 publications

Raman investigation of defective SiC nanocrystals

Raman investigation of defective SiC nanocrystals

Evaluation of thermal conductivity of the constituent layers in TRISO particles using Raman spectroscopy

Determination of thermal conductivity using micro‐Raman spectroscopy with a three‐dimensional heating model

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