Specific structural features and thermal resistance of shungite carbon to graphitization

Холодкевич, С. В.; Berezkin, V. I.; Davydov, V. Yu.

doi:10.1134/1.1130984

Cited by 16 publications

(16 citation statements)

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“…This material has specific properties. It was shown, that higher anthraxolites are non‐graphitizable up to 2700 °C . The electrical conductivity was found to be similar to the conductivity of graphite in the direction perpendicular to graphite layers .…”

Section: Introductionmentioning

confidence: 91%

“…It was shown, that higher anthraxolites are non-graphitizable up to 2700°C. [35] The electrical conductivity was found to be similar to the conductivity of graphite in the direction perpendicular to graphite layers. [36] Other reported studies dealt with the globular structure, [34,37] paramagnetic properties, [37,38] thermal conductivity, [39][40][41] and acoustical properties.…”

Section: Samplesmentioning

confidence: 99%

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Size effects in the conduction electron spin resonance of anthracite and higher anthraxolite

Tadyszak

Strzelczyk

Coy

et al. 2015

Magnetic Reson in Chemistry

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Electron paramagnetic resonance spectroscopy of conduction electrons, i.e. Conduction Electron Spin Resonance (CESR), is a powerful tool for studies of carbon samples. Conductive samples cause additional effects in CESR spectra that influence the shape and intensity of the signals. In cases where conduction electrons play a dominant role, whilst the influence of localized paramagnetic centres is small or negligible, the effects because of the spins on conduction electrons will dominate the spectra. It has been shown that for some ratios of the bulk sample sizes (d) to the skin depth (δ), which depend on the electrical conductivity, additional size effects become visible in the line asymmetry parameter A/|B|, which is the ratio of the maximum to the absolute, minimum value of the resonance signal. To study these effects the electrical direct current-conductivity and CESR measurements are carried out for two amorphous bulk coal samples of anthracite and a higher anthraxolite. The observed effects are described and discussed in terms of the Dyson theory. Copyright © 2015 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 91%

Section: Samplesmentioning

confidence: 99%

Size effects in the conduction electron spin resonance of anthracite and higher anthraxolite

Tadyszak

Strzelczyk

Coy

et al. 2015

Magnetic Reson in Chemistry

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“…The Raman spectra for all shungite samples are consistent with poorly ordered CM, [17,21,36,37] because the first-order region of the shungite Raman spectra shows two well-resolved bands D1 at 1350 cm À1 and G band at~1580 cm À1 . In the second-order region, shungite samples are mainly characterized by bands located at~2700 and~2900 cm À1 (Figs 1-3).…”

Section: Theory: Raman Spectrum Of Carbonaceous Materialsmentioning

confidence: 59%

Raman spectroscopy of weathered shungites

Chazhengina

Kovalevski

2017

J Raman Spectroscopy

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Raman spectroscopy has proven to be a useful tool for the study of carbonaceous material (CM). This method is used to distinguish various types of CM and to study the evolution of Raman spectra characteristics of CM during metamorphic transformations. In the present study, we applied the Raman spectroscopy and electron diffraction methods to investigate the evolution of structural ordering of CM of shungite rocks, Karelia (Russia), during weathering. The studies of the CM structure evolution during weathering are rare and ambiguous. The Raman spectra of weathered shungites are characterized by increase of FWHM‐D1, that is accompanied by the decrease of intensity‐based ratio R1 = ID/IG and the change of the intensity of the bands in second‐order region. The Raman spectral data indicate that weathering results in the alteration of both intralayer and interlayer ordering of shungites, but there are some peculiarities for the shungites subjected to the various types of weathering. The present study establishes that the Raman spectra characteristics of weathered shungites can be used as the indicators of weathering for CM from various carbon‐bearing rocks. Copyright © 2017 John Wiley & Sons, Ltd.

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“…The XRD pattern of the prepared sample shown in figure 1a points to the presence of a cubic (3C) polytype of SiC as major crystalline phase and also hexagonal (2H) polytype of SiC and iron silicide (FeSi) as minor ones. Thus, obtained results are compared with data presented in the literature (Kalinin et al 1999;Kholodkevich et al 1999).…”

Section: Major Phase Compositionmentioning

confidence: 80%

“…The second requirement needs to gather analytical information on the structural and compositional transformation of shungite during thermal processing. Although the literature related to this subject is extensive (Kalinin et al 1999;Kholodkevich et al 1999;Nikitin et al 2007;Polonskii et al 2007), behaviour of the minor and accessory phases has not been sufficiently described. We also found no relevant data on purity of products obtained by the heat treatment of shungite.…”

Section: Introductionmentioning

confidence: 99%

SEM investigation of minor constituents of carbide materials prepared from shungite rocks

et al. 2011

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The "SiC-Al 2 OC"-based composite prepared from Karelian shungite rocks has been studied by X-ray diffraction analysis and scanning electron microscopy. SEM investigation has been done to determine the mode and distribution of admixture constituents. It is found that the most common minor phase represents Al-Fe-Si-C-based alloys. Special attention has been given to describing the noble metals admixtures. It is revealed that the noble metals phases occur as separate microsized grains, most of which have been indicated as Au-Ag-Hg amalgam and rarely as Pt-rich compounds. The obtained data can be mainly used to advance technologies for manufacturing carbide-based composite materials from natural carbonaceous rocks. Keywords. Shungite rocks; thermal processing; carbide materials; SiC-Al 2 OC; admixtures; noble metals.

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Specific structural features and thermal resistance of shungite carbon to graphitization

Cited by 16 publications

References 1 publication

Size effects in the conduction electron spin resonance of anthracite and higher anthraxolite

Size effects in the conduction electron spin resonance of anthracite and higher anthraxolite

Raman spectroscopy of weathered shungites

SEM investigation of minor constituents of carbide materials prepared from shungite rocks

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