Deformations and Thermal Modifications of Imogolite

Rouzière, Stéphan; Amara, Mohamed-Salah; Paineau, Erwan; Launois, Pascale

doi:10.1016/b978-0-08-100293-3.00011-x

Cited by 6 publications

(9 citation statements)

References 35 publications

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“…Moreover, their positions shift toward the position of the closest maximum of the squared form factor, as expected from eq . In this way, Q 10 and Q 20 increase while Q 11 and Q 21 decrease for decreasing number of INTs per bundle . It follows that the lattice parameter cannot be simply derived from the position of the 10 peak in the case of small bundles.…”

Section: Theoretical Methodsmentioning

confidence: 94%

“…Such a derivation would lead to an underestimation of a of the order of 10% (Figure 4). 57 This point, well-recognized in previous works on carbon nanotubes, 55 appears still disregarded in the case of imogolite nanotubes. 11,15,26 It may also be noted that conclusions concerning the packing angle α are not unambiguous when based on XRS from small bundles.…”

mentioning

confidence: 96%

“…In this way, Q 10 and Q 20 increase while Q 11 and Q 21 decrease for decreasing number of INTs per bundle. 57 It follows that the lattice parameter cannot be simply derived from the position of the 10 peak in the case of small bundles. Such a derivation would lead to an underestimation of a of the order of 10% (Figure 4).…”

mentioning

confidence: 99%

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Effect of Ionic Strength on the Bundling of Metal Oxide Imogolite Nanotubes

et al. 2017

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Significant developments have been proposed over the past decade in the synthesis of aluminosilicate and aluminogermanate imogolite-like nanotubes. But, while liquid phase synthesis is well-controlled, it is not the case for the nanotube arrangement in the dry state. In particular, nanotubes are found to self-assemble in bundles of various sizes, which may impact the properties of the final product. Here, we investigate the effect of ionic strength on bundling of aluminogermanate single-walled imogolite nanotubes (Ge-SWINT) in aqueous suspensions and in the resulting powders after solvent evaporation. The nanotube arrangement as a function of salt concentration was studied by X-ray scattering experiments and simulations. In aqueous suspension, nanotubes bundling occurs only at high ionic strength (IS > 8 × 10–2 mol·L–1), while beyond this threshold, the increase of electrostatic repulsions induces a complete stabilization of individual nanotubes. After solvent evaporation, nanotube arrangement is shown to be dictated principally by the initial concentration of salt. Beyond an ionic strength of ∼10–3 mol·L–1 in the starting suspension, all Ge-SWINT samples tend to form large bundles in powder, whose lattice parameters are independent of the initial salt concentrations. These experimental results clearly show that the positive surface charge of imogolite can be used to control nanotubes bundling by anion condensation.

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Section: Theoretical Methodsmentioning

confidence: 94%

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confidence: 96%

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Effect of Ionic Strength on the Bundling of Metal Oxide Imogolite Nanotubes

et al. 2017

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“…The thermal stability of imogolite nanotubes has been addressed extensively since their discovery, highlighting the expected phase sequence with dehydration around T ∼ 120 °C then dehydroxylation ( T = 300–500 °C) of the nanotubes before transformation into mullite for temperatures above 900 °C. , Like other clay nanomaterials, these nanotubes undergo major structural transformations during dehydroxylation stage. An amorphous phase was observed from X-ray scattering experiments on INT samples thermally treated at 350 °C or around 500 °C, related to a probable collapse of the nanotube structure .…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Structural Reordering During Thermal Transformation of Aluminogermanate Imogolite Nanotubes

et al. 2021

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Metal oxide aluminosilicate and aluminogermanate nanotubes, called imogolite nanotubes, are custom made nanotubes with controlled diameter, morphology and organization. These nanotubes undergo major structural changes at high temperatures. Here, we report a complete analysis of the structural transformation of single and double-walled aluminogermanate nanotubes, organized or not in bundles, up to 800 • C. Complementary X-ray scattering and spectroscopy experiments were performed. The evolution of both Al and Ge atoms coordination during the transformation process was studied in-situ. Quantitative analysis of X-ray absorption spectra reveals that the dehydroxylation of nanotubes leads to intermediate stages of 'metaimogolite', which differ in the coordination of the aluminium atoms. A mechanism explaining the major structural reorganization is proposed based on atomic jump processes.

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“…Tetrahedron orientation in INTs is thus exceptional for a clay mineral. The thermal stability of imogolite nanotubes has been addressed extensively since their discovery, 28 highlighting the expected phase sequence with dehydration around T ∼ 120 • C then dehydroxylation (T = 300 − 500 • C) of the nanotubes before transformation into mullite for temperatures above 900 • C. 13,29 Like other clay nanomaterials, these nanotubes undergo major structural transformations during dehydroxylation stage. An amorphous phase was observed from X-ray scattering experiments on INT samples thermally treated at 350 • C 30 or around 500 • C, 29 related to a probable collapse of the nanotube structure.…”

Section: Introductionmentioning

confidence: 99%