Raman studies of coals

Żerda, T. W.; John, A.; Chmura, Kazimierz

doi:10.1016/0016-2361(81)90272-6

Cited by 74 publications

(37 citation statements)

References 11 publications

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“…It broadens with increasing disorder. [71] The D2 band arises in disordered carbons, at ca. 1600-1635 cm À1 (therefore overlapping with the G band, Table 3) and is associated also with the D1 feature, which means that all the studied pigments samples have a D2 band component, because they all show disorder bands between 1300 and 1400 cm À1 .…”

Section: Resultsmentioning

confidence: 99%

“…I Defects [43,52,54] ; soot features, [33,51,56] like mixed sp 2 -sp 3 bonds or polyenic structures [45,47,58] ; char and coal tar [48] ; diamondlike carbon in anthracite [71] ; sp 3 carbons [59,72] ; nanocrystalline diamond or trans polyene ν 1 [57] ; defects related to oxygen rich precursors as wood [60,61] From 1050 with deep UV excitation [57] to 1127 [51] to 1275 [48] [23,33,45,47,[52][53][54][55][56][57][58][59][60][61]71,72] Fullerenes Phototransformation/oxidation [38,73] 1459-1469 and 930-970 [38,73] Rhombohedral graphite B 2 2g [48] 1400 [48] ; [49] 1800 1400 1200 1000 800 1600…”

Section: D4mentioning

confidence: 99%

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Raman spectroscopy for the investigation of carbon‐based black pigments

Coccato

Jehlička

Moëns

et al. 2015

J Raman Spectroscopy

179

136

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a Raman spectroscopic studies of carbonaceous materials are, until now, mainly devoted to geological and industrial materials. On the other hand, it is known from artistic literature that many varieties of carbon-based black pigments were produced and used in different places and times, and according to the artist's preferences. The ability of Raman spectroscopy to analyse particles down to 1 μm and its non-destructiveness make it an ideal tool for pigments investigation. Anyway, the discrimination among different types of carbon-based black pigments is affected by various aspects, one of which is the lack of reference spectra as well as of specific nomenclature. In this paper, reference materials have been studied by means of Raman spectroscopy to provide reference spectra. All the pigments showed two broad bands of carbon, but sometimes specific excitation conditions were required to record a good quality Raman spectrum. The obtained Raman signatures are discussed, on the basis of the specificities of the pigment (natural or artificial origin; structural implications related to the raw materials used or to production processes; etc.). Therefore, on the basis of the Raman spectra of painting materials, further knowledge can be obtained on the type of carbon-based black pigments in works of art.

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Section: Resultsmentioning

confidence: 99%

Section: D4mentioning

confidence: 99%

Raman spectroscopy for the investigation of carbon‐based black pigments

Coccato

Jehlička

Moëns

et al. 2015

J Raman Spectroscopy

179

136

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show abstract

“…Tsu et al [19] speculated that the 1370 cm −1 band (disordered induced) could be explained by phonon dispersion of graphite and postulated a typical cluster size for a coal molecule in the order of 65-72´Å. In 1981, Zerda et al [20] gave a short review of the preceding Raman studies of coal, and reported on their investigations on several Polish coals, including samples where the inertinite and vitrinite macerals had been separated. No evident relationship between coal rank and the G and D band positions were reported, but the authors did indicate a broadening of both bands as they moved to the lower ranked coals.…”

Section: Methodsmentioning

confidence: 99%

“…[13] Various papers were referenced that applied this method to determine the crystallite size along graphite basal planes and indicated the contradictory results obtained for various carbon materials if compared to XRD measurements, i.e. higher values were obtained for coal [20] and carbon fibers, [37] and lower values for graphites. [38] The authors emphasized that Tuinstra and Koenig's [13] formula can only be used as a first approximation of L a and the accuracy of such estimation depends heavily on the type of carbon under study.…”

Section: -1999 (Continuation Of the Work Of The 1980s)mentioning

confidence: 99%

Raman spectroscopy for the analysis of coal: a review

Potgieter‐Vermaak

Maledi

Wagner

et al. 2011

J Raman Spectroscopy

254

126

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The advances in the characterization of amorphous carbons by Raman spectroscopy over the last four decades are of interest to many industries, especially those involving the combustion, gasification and pyrolysis of coal. Many researchers report on the Raman character of the natural organic matter in carbon-containing compounds, such as coal, and relate the Raman bands to the structural order of the amorphous carbons. The basis of most of these studies evolved around the assignment of the G (graphitic, ∼1580 cm −1 ) band to crystalline graphite and any other bands, called D bands, (disorder, various from 1100 to 1500 cm −1 ) to any type of structural disorder in the graphitic structure. Concerning coal analysis, the information gained by Raman investigations has been used to describe char evolution as a function of temperature, the presence of catalysts and different gasification conditions. In addition, researchers looked at maturation, grade, doppleritization and many more aspects of interest. One aspect that has, however, not been addressed by most of the researchers is the natural inorganic matter (NIM) in the carbon-containing compounds. Micro-Raman spectroscopy (MRS) has many advantages over other characterization tools, i.e. in situ analysis, nondestructive, no sample preparation, low detection limit, micrometer-scale characterization, versatility and sensitivity to many amorphous compounds. With the distinct advantages it has over that of other molecular characterization tools, such as powder X-ray diffraction (PXRD), Fourier-transform infrared spectrometry (FT-IR) and scanning electron microscopy with X-ray detection (SEM/EDS), it is surprising that it has not yet been fully exploited up to this point for the characterization of the NIM in coal and other amorphous carbons. This paper reviews the work published on the Raman characterization of the natural organic matter (NOM) of coals and reports on preliminary results of the NIM character of various South African coals, whereby various inorganic compounds and minerals in the coal have been characterized.

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“…The crystalline-amorphous carbon structure observed during carbonization was further studied with the help of X-ray and Raman crystallography.Some structural parameters of chars can be also obtained by means of Raman spectroscopy [18]. The assignment of the 10 bands in the Raman spectroscopy of chars is summarized [9].…”

Section: Raman and X-ray Analysis Of Charsmentioning

confidence: 99%

Effect of Cross-linking Reactions on Evolution Mechanism of Crystalline-Amorphous Carbon during Bituminous Coal Carbonization

Liu¹,

Gao²,

Wu³

et al. 2015

Proceedings of the 2015 2nd International Workshop on Materials Engineering and Computer Sciences

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Abstract. Crystalline carbon and amorphous carbon are two of the major carbon structures found in coal. The influence of cross-linking reactions (CLRs) on the evolution mechanism of crystalline-amorphous carbon during bituminous coal carbonization was studied using X-ray and Raman crystallographic methods. These results showed that firstly low-temperature CLRs enhanced the transformation of amorphous carbon into crystalline carbon at the begin of carbonization, then affected the mean size of crystalline structures, and finally facilitated degradation processes that resulted in the transformation of crystalline carbon into amorphous carbon. However, different effects were observed for moderate-temperature CLRs on crystalline-amorphous carbon. Firstly, the disruption of weak bonds led to the transformation of crystalline carbon into amorphous carbon. Then moderate-temperature CLRs led to the appearance of small layers in amorphous carbon structures and initiated the transformation of amorphous carbon into crystalline carbon. Finally, the amount of crystalline carbon with respect to amorphous carbon continued to grow.

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Raman studies of coals

Cited by 74 publications

References 11 publications

Raman spectroscopy for the investigation of carbon‐based black pigments

Raman spectroscopy for the investigation of carbon‐based black pigments

Raman spectroscopy for the analysis of coal: a review

Effect of Cross-linking Reactions on Evolution Mechanism of Crystalline-Amorphous Carbon during Bituminous Coal Carbonization

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