Single-walled hollow nanospheres assembled from the aluminogermanate precursors

Bac, Bui Hoang; Song, Yungoo; Kim, Myung Hun; Lee, Young Boo; Kang, Il‐Mo

doi:10.1039/b908997g

Cited by 11 publications

(11 citation statements)

References 24 publications

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“…This also accompanied by a decrease of the vibration at 690 cm −1 and the appearance of a new peak located at 745 cm −1 (arrows in Figure 4). These features were attributed previously to a specific mode either for aluminogermanate single-walled INTs formed when decreasing the hydrolysis ratio [35] or aluminogermanate nanospheres synthesized in basic conditions [33]. In the present case, the absorption band observed at 745 cm −1 is highly pronounced for R' = 0.9 for which we have observed the presence of single-walled nanotubes based on WAXS experiments, but it also remains significant for the lowest value of R' while only plate-like structures are observed (Figure 2a).…”

Section: Structural Properties Of Final Productssupporting

confidence: 52%

“…Increasing or decreasing the hydrolysis ratio can lead to nanotubes with variable amount of defects or to the hindering of the formation of nanotubes for R < 1.5 and R > 2.5 [32]. It was also suggested that, under basic conditions, hollow nanospheres are formed instead of nanotubes when the precursor ratio R' = [Al]/[Ge] is lowered below 2 [33], which is the ratio of Al and Ge atoms within a non-defective Ge-based INT with formula Ge(Al)2O7H4. Finally, while Si-based INTs are singlewalled (SW) nanotubes, germanium-based nanotubes are obtained as single-walled (SW) or doublewalled (DW) nanotubes depending on the initial concentration of aluminum C[Al] (Figure 1b) [34,35], the latter having an internal diameter of 1.5 nm for an external diameter of 4.3 nm and a limited average length of ~ 20 nm [36].…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Al/Ge Ratio on the Structure and Self-Organization of Anisometric Imogolite Nanotubes

Paineau

Launois

2020

Crystals

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Synthetic imogolite-like nanotubes (INT) with well-defined diameters represent a considerable opportunity for the development of advanced functional materials. Recent progress has made it possible to increase their aspect ratio and unique self-organization properties were evidenced. We suggest that slight modification of the synthesis conditions may drastically affect the resulting liquid-crystalline properties. In this work, we investigate how the precursor’s [Al]/[Ge] molar ratio (R’) impacts the morphology and the colloidal properties of aluminogermanate INTs by combining a multi-scale characterization. While only double-walled nanotubes are found for R’ ≥ 1.8, the presence of single-walled nanotubes occurs when the ratio is lowered. Except for the lowest R’ ratio investigated (R’ = 0.66), all synthetic products present one-dimensional shapes with a high aspect ratio. Small-angle X-ray scattering experiments allow us to comprehensively investigate the colloidal properties of the final products. Our results reveal that a liquid-crystalline hexagonal columnar phase is detected down to R’ = 1.33 and that it turns into a nematic arrested phase for R’ = 0.90. These results could be useful for the development of novel stimuli-responsive nanocomposites based-on synthetic imogolite nanotubes.

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Section: Structural Properties Of Final Productssupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Influence of the Al/Ge Ratio on the Structure and Self-Organization of Anisometric Imogolite Nanotubes

Paineau

Launois

2020

Crystals

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“…5 It indicates strongly that Ge-incorporation should play a crucial role in stabilizing the akaganeite structure. The band at 858 cm À1 and a weak shoulder at about 950 cm À1 for the 1000 C heated sample may be assigned to the Ge-O stretching, 19 which would be due to the appearance of Ge-oxide (Fig. 7).…”

Section: Thermal Propertiesmentioning

confidence: 99%

Highly ordered Ge-incorporated akaganeite (β-FeOOH): a tunnel-type nanorod

et al. 2011

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A highly ordered Ge-incorporated akaganeite with the atomic ratio of Ge/Fe ¼ 0.14 and Cl/Fe ¼ 0.11 was firstly synthesized through hydrolysis and acidification of a mixed solution of FeCl 3 $6H 2 O and TEOGe (Ge(OC 2 H 5 ) 4 ) under the a-Fe 2 O 3 synthesis conditions. The newly synthesized Ge-akaganeite shows a monodisperse nanorod with 15-17 nm in width and $200 nm in length, the distinctly enhanced structural ordering and stability, and substantial differences in crystallographic and magnetic features.Here we propose a hypothetical akaganeite model with Ge occupying the tunnel sites as Ge(OH) 4 0 based on crystallographic and chemical analyses.

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“…DFT simulations have been coupled to experiments to propose a mechanism for the selection of the two types of curvature (spherical and tubular). It is concluded that the ions and pH seems to play an important role (Abidin et al, 2007;Bac et al, 2009). The use of Si-CH 3 groups for the internal surface of the ILS nanominerals maintains a spontaneous curvature without the formation of H bond network and electrostatic interactions.…”

Section: Introductionmentioning

confidence: 97%

A mechanism for the sphere/tube shape transition of nanoparticles with an imogolite local structure (imogolite and allophane)

Thill

Picot

Belloni

2017

Applied Clay Science

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International audienceImogolite and allophane are two strongly curved nanominerals. Indeed, imogolite has a tubular shape with a diameter of only 2.5 nm. Allophane is often presented as a spherical nanostructure with a diameter of about 5 nm. The mechanism explaining the strong curvature of these two nanominerals has been extensively discussed. However , whether or not these two nanomaterials are related to each other is not clear and the mechanism responsible for the selection between the two different shapes is not well established. In this article, we propose that imogolite and allophane are nanopolymorphs of the imogolite local structure and that the transition from spherical to tubular shape occurs at an early stage of the precipitation because of edge stress in proto-imogolite. This hypothesis for the shape selection is supported by the use of a nanomechanical model tuned to mimic the main characteristics of imogolite-like nanomaterials

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Single-walled hollow nanospheres assembled from the aluminogermanate precursors

Cited by 11 publications

References 24 publications

Influence of the Al/Ge Ratio on the Structure and Self-Organization of Anisometric Imogolite Nanotubes

Influence of the Al/Ge Ratio on the Structure and Self-Organization of Anisometric Imogolite Nanotubes

Highly ordered Ge-incorporated akaganeite (β-FeOOH): a tunnel-type nanorod

A mechanism for the sphere/tube shape transition of nanoparticles with an imogolite local structure (imogolite and allophane)

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