Formation and Growth Mechanisms of Imogolite-Like Aluminogermanate Nanotubes

Abstract

The growth mechanisms of imogolite-like aluminogermanate nanotubes have been examined at various stages of their formation. The accurate determination of the nucleation stage was examined using a combination of local- (XAS at the Ge−K edge and 27Al NMR) and semilocal scale technique (in situ SAXS). For the first time, a model is proposed for the precursors of the nanotubular structure and consist in rooftile-shaped particles, up to 5 nm in size, with ca. 26% of Ge vacancies and varying curvatures. These precursors assemble to form short nanotubes/nanorings observed during the aging process. The final products are most probably obtained by an edge−edge assembly of these short nanotube segments.

Evidence of Double-Walled Al−Ge Imogolite-Like Nanotubes. A Cryo-TEM and SAXS Investigation

“…These particles very likely correspond to the structurally ill-defined precursors from which the NTs form 3b,5b and for which a generic structure in the form of roof tile shaped fragments has been recently proposed. 7 SAXS measurements gave further quantitative insight into the structure of the NTs. The SAXS analysis on solutions has been performed on the BM02 beamline at the European Synchrotron Radiation Facility (ESRF, Grenoble, France).…”

Nanotubular Aluminosilicates: A Case Study for Science and Industry

“…The presence and intensity of XRD peaks of this nanotube are close related to the condition of sample 35,36 . The shape and intensity of the first peak (at 20 nm) are always related to the external diameter and the tubular structure characteristic peaks (d = 2.00, 0.90, 0.63 and 0.39 nm), are assigned to (010), (020), (030), and (032), respectively 4 (see Figure 3, right).…”

Clay Mineral Nanotubes: Stability, Structure and Properties

“…The fact that the synthesis occurs in aqueous solution means that the pH and, consequently, the involved species acidic constants (pKa=-log(Ka)) are very important and guide the hydrolysis. Recently, the imogolite-like structure aluminogermanate has been synthesized (Levard et al, 2008;Levard et al, 2010). Here, the SiO 4 4-is replaced by GeO 4 4-fragments.…”

“…The synthesis of new imogolite-like structures is an important issue and deserves more attention. Actually, the aluminogermanate NTs (Levard et al, 2008;Levard et al, 2010) are an important example of the feasibility of this task and more effort in this direction must be done. In fact, lamellar gibbsite can be seen as a template for modeling and synthesizing new nanostructured imogolite-like structures.…”