Atomic force microscopy of synthetic imogolite

Tani, Masaaki; Liu, C.; Huang, P. M.

doi:10.1016/s0016-7061(03)00204-0

Cited by 22 publications

(20 citation statements)

References 28 publications

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“…7, the theoretical x-ray-P are compared with two experimental x-ray-P for the case of Imo-Si. The sequence of patterns ͑I͒ shows the comparison of the experimental x-ray-P obtained by Tani et al 38 for synthetic 100% Si imogolite and K␣-Fe with the x-ray-P calculated in this work for the same source. In this sequence a shift of the two main calculated peaks in the region 5°Ͻ 2 Ͻ 30°can be observed, and a third peak starts to appear at N u =11 in the region 15°Ͻ 2 Ͻ 20°and it is well-defined at N u = 13.…”

Section: Structural Generation Of Modelsmentioning

confidence: 65%

“…The x-ray technique has been extensively used by experimental groups in the characterization of both isolated and bundles of imogolite-like tubes and their structural evolution during their synthesis, 13,27,30,31,37,38 the results obtained using this technique depend on whether the imogolite-like samples are isolated tubes or bundles. The isolated tubes are obtained by dispersion with ultrasonification in an ice bath 38 from a common bundle arrangement.…”

Section: Structural Generation Of Modelsmentioning

confidence: 99%

“…This result is in accordance with what has been accepted as the most likely value of N u = 10 for natural imogolite. 14,40 In the mesoscale level, imogolites are characterized by bundles containing 3-20 tubes essentially randomly oriented; 9,13,15,22,30,31,38,[41][42][43] in some cases local ordering appears in the tube orientation. 17 The mesoscale structural properties of oriented tubes have been simulated by Hoshino et al 44 assembling the cylindrical tubes aligned in a packed hexagonal structure, testing different bundle configurations and comparing the simulated pair distribution functions with experimental ones obtained by small angle x-ray scattering.…”

Section: Structural Generation Of Modelsmentioning

confidence: 99%

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Ab initiosimulation of the structural and electronic properties of aluminosilicate and aluminogermanate natotubes with imogolite-like structure

Alvarez-Ramírez

2007

Phys. Rev. B

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A theoretical study of imogolite-like single wall nanotubes as a function of silicon and germanium content and their tubular radius is presented along with mapping of silicon-germanium content properties in models that contain from 9 gibbsite-like units ͑N u =9͒ to 13 gibbsite-like units ͑N u =13͒ with a silicon-germanium content ͓X =Si/͑Si+ Ge͔͒ of 0, 0.20, 0.40, 0.60, 0.80, and 1.00. The imogolite nanotubes were built setting periodic boundary conditions to density functional theory ͑DFT͒ geometry-optimized models along both radial and axial directions in order to obtain the stable structure. The DFT calculations were carried out on the ⌫ point and for various k points, using the GGA-PW91 functional, finding an optimal unit cell length of 8.72 and 8.62 Å using a double numeric ͑DN͒ and double numeric with polarization ͑DNP͒ basis set, respectively, along the axial direction. The structural properties were analyzed through the evolution of the x-ray diffraction pattern as a function of both N u and X. A linear correlation between the tube radius and the position of the first two peaks on the x-ray diffraction is found. The imogolite surface charge was mapped with the Hirshfeld charge showing the characteristic acid tendency experimentally reported. The reactivity of imogolite-like structures was studied employing the total density of states and the band gap evolution as a function of N u and X showing an increasing behavior with X. The local reactivity was analyzed by looking at the local density of states in models with X = 0.0 and 1.0 with N u = 10. Finally, the frequency analysis was carried out in the optimized structure on the ⌫ point finding a good agreement in the O-H vibrations with those reported in the literature.

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Section: Structural Generation Of Modelsmentioning

confidence: 65%

Section: Structural Generation Of Modelsmentioning

confidence: 99%

Section: Structural Generation Of Modelsmentioning

confidence: 99%

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Ab initiosimulation of the structural and electronic properties of aluminosilicate and aluminogermanate natotubes with imogolite-like structure

Alvarez-Ramírez

2007

Phys. Rev. B

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“…The broad band at 570 cm −1 with shoulders at 690 and 430 cm −1 indicates an imogolite-like structure observed in natural allophane and imogolite [27]. Compared to allophane, imogolite peaks are sharper with doublets at 970 and 570 cm −1 [32,34]. Sharper peaks for 0.75 mM initial Al solids may indicate more imogolite or imogolite-like material in these samples.…”

Section: Ftir Analysismentioning

confidence: 98%

The Effect of Dissolved Humic Acids on Aluminosilicate Formation and Associated Carbon Sequestration

Rouff

Phillips

Cochiara

et al. 2012

Applied and Environmental Soil Science

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Allophane and imogolite neogenesis in soils may occur in the presence of organic matter. To understand this process under conditions relevant to soils, the influence of dissolved organic carbon (DOC) as humic acid (HA), on aluminosilicate formation was studied at 25• C, pH 6, and low-DOC concentrations. For solutions with initial Al/Si ratios of 1-2.1, and 0-6 mg/L DOC, precipitates recovered after 20 h had Al/Si ratios of 2.2-2.7. The formation of allophane, imogolite-like material, and aluminosilicate gel was confirmed by XRD, FTIR, and NMR. The effect of DOC was to produce a small, but systematic increase in imogolite-like Si in the precipitate, and a decrease in the formation of aluminosilicate gel. Results suggest that the presence of DOC as HA slows the otherwise rapid polymerization of Al and Si at low temperature, and may also promote the formation of imogolite. The high C content of these precipitates indicates that this process may facilitate the sequestration of organic matter, slowing C cycling in soils.

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“…The tapping-mode AFM especially shows the morphological features of the synthetic imogolite clearly [26,27]. Figure 4 shows the tapping mode AFM image of synthetic imogolite.…”

Section: Morphologymentioning

confidence: 98%

Synthesis and Characterization of Fe-Imogolite as an Oxidation Catalyst

Ookawa¹

2012

Clay Minerals in Nature - Their Characterization, Modification and Application

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Atomic force microscopy of synthetic imogolite

Cited by 22 publications

References 28 publications

Ab initiosimulation of the structural and electronic properties of aluminosilicate and aluminogermanate natotubes with imogolite-like structure

Ab initiosimulation of the structural and electronic properties of aluminosilicate and aluminogermanate natotubes with imogolite-like structure

The Effect of Dissolved Humic Acids on Aluminosilicate Formation and Associated Carbon Sequestration

Synthesis and Characterization of Fe-Imogolite as an Oxidation Catalyst

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