SAXS analysis of graphitic amorphous carbon

Oliveira, M. A. L.; Barbieri, P.F.; Torriani, Íris L.; Marques, F. C.

doi:10.1016/j.tsf.2007.06.081

Cited by 10 publications

(4 citation statements)

References 14 publications

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“…10,20 We denote the second region as the SAXS (mesoscopic) regime located at 0.01 ≲ q ≤ 0.26 Å −1 , which includes low to intermediate scattering vectors where the intensity profile can be interpreted as correlations due to a continuous electron density between the matrix and scattering centers. 39 The SAXS region was analyzed using power law dependencies (eq 3 in Supporting Information). We refer to these power law fits as levels and associate them with hierarchical structures measured at distinct length scales and forming fractal structures.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The intensity profiles exhibit a concave curvature, generally ascribed to particle aggregation. , Particle aggregates are represented by clusters of particles closely packed, and groups of these are called agglomerates. After ball milling the carbon materials, aggregates and agglomerates are visible in micrographs (example in Figure ), where particle size distribution ranges from 64 to 178 nm. , We denote the second region as the SAXS (mesoscopic) regime located at 0.01 ≲ q ≤ 0.26 Å –1 , which includes low to intermediate scattering vectors where the intensity profile can be interpreted as correlations due to a continuous electron density between the matrix and scattering centers . The SAXS region was analyzed using power law dependencies (eq 3 in Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

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Development of Nanocrystalline Graphite from Lignin Sources

García‐Negrón

Chmely

Ilavský

et al. 2022

ACS Sustainable Chem. Eng.

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Carbon composites are attractive to a variety of high-impact applications, such as carbon fibers, batteries, and vehicle parts, due to their multifunctional properties. The properties of carbon are highly dependent on the allotrope the carbon takes and the functionality, impurities, and defects contained within the structure. The increase in demand for sustainable carbon sources in energy storage devices motivates interest in understanding synthesis parameters of lignin value-added products. Also, as the dependence on oil for fuel decreases, alternative sources for carbon in many applications will be needed. In this work, the thermochemical conversion of lignin powders from different feedstocks was evaluated via small and wide-angle X-ray scattering techniques to resolve the amorphous, disordered, and crystalline domains present in the lignin carbons. Scattering analyses indicated an evolution of hierarchical structures along with an increase in ordered domains as a function of carbonization temperature. Qualitative and quantitative methods were used to describe isotropic scattering intensity profiles at multiple length scales. The use of power law models in the mesoscopic region served as the basis to describe morphological changes related to structural features, for example, graphene stacking, degree of roughness, and surface fractals. Kraft softwood and switchgrass produced carbon powder with the most crystalline domains and the least surface roughness. Softwoods reached the highest degree of crystallinity followed by switchgrass samples and had less variability in particle sizes. These results suggest lignin carbons extracted from softwoods and switchgrass are viable substitutes for graphite. Interpretation of X-ray scattering data from lignin carbon powders elucidates feedstock-and processing-dependent morphological features across multiple length scales providing a straightforward framework to evaluate the feasibility of leveraging lignin carbons for producing tunable application-specific materials.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Development of Nanocrystalline Graphite from Lignin Sources

García‐Negrón

Chmely

Ilavský

et al. 2022

ACS Sustainable Chem. Eng.

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“…This is the result of azimuthal mis-alignment of the neighboring layers in relation to one another. According to the results of the natural carbon structure investigation, [13] non-monotonic change in the intensity of the background scattering is the evidence for the existence of the amorphous carbon phase.…”

Section: Samplementioning

confidence: 99%

Changes in the Electrical Charge Accumulation Ability of Nanoporous Activated Carbon under Ultrasonic Radiation Exposure

Bordun

Chabecki

Malovanyy

et al. 2020

Israel Journal of Chemistry

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The influence of ultrasonic radiation in the cavitation regime on the structural and electrochemical properties of activated carbon was studied. It was established, as the result of the X‐ray diffraction and nitrogen adsorption/desorption analysis, that the ultrasound treatment causes substantial changes in the atomic and porous structure of the samples. The ultrasound treatment resulted in an increase of the graphitization degree of the carbon material and thus, in an increase of its density. The specific surface area and specific volume of the investigated samples decreased after the ultrasound treatment. The impedance dependencies for the supercapacitors made either from the initial and the modified carbon have been analyzed. The equivalent electrical circuits modelling the Nyquist diagrams have been constructed. De Levie impedance model, modified by series connection of parallel RC‐circuit, was used. It has been shown that ultrasonic radiation changes the Fermi level position by shifts to the energy region with high states density of delocalised electrons. This is the reason for unblocking of the Helmholtz layer capacitance due to the increase in the capacitance of the layer of the space charge region in the carbon material. It was shown that ultrasound treatment allows also controlling successfully the admixture and native defects distribution, existing on material surface and which are responsible for the surface electron states formation.

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“…To study structural changes, except for XRD 17) and TEM, 18) a wide range of techniques are currently used: small-angle X-ray scattering (SAXS), 19) small-angle neutron scattering, 20) and gas adsorption/desorption analysis. 21) Each of these methods has its advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Structural behaviors in water adsorbing phenomena on nanoporous carbon fabricated from waste rice husk

Li¹,

Yamazaki²,

Komatsu³

et al. 2021

Jpn. J. Appl. Phys.

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The nanoporous carbon (NPC) performance, used for drug delivery carriers, wastewater treatment, or hydrogen storage, is strongly determined by the pore morphology during the desorption. In this work, the structural characteristics of NPC fabricated from rice husk by KOH activation were studied. X-ray diffractometry (XRD) and small-angle X-ray scatter were then implemented to characterize the pore size and adsorbate model under a series of adsorption–desorption conditions, combined with the details of the multilayer pore morphology obtained from gas adsorption. To this aim, the water was selected as adsorbate, which could be investigated under desorption conditions. The results confirmed that NPC changed from an amorphous structure to a regularly arrayed monolayer structure by introducing adsorbates and returns to their origin after thoroughly drying. A detailed understanding of the behavior of adsorbent and adsorbate may facilitate its storage ability and application in selective sorption, separation, and storage processes.

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SAXS analysis of graphitic amorphous carbon

Cited by 10 publications

References 14 publications

Development of Nanocrystalline Graphite from Lignin Sources

Development of Nanocrystalline Graphite from Lignin Sources

Changes in the Electrical Charge Accumulation Ability of Nanoporous Activated Carbon under Ultrasonic Radiation Exposure

Structural behaviors in water adsorbing phenomena on nanoporous carbon fabricated from waste rice husk

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