Nanoscaled Sn and Pb particles aligned in Al2O3 tubes obtained from molecular precursors

Veith Michael, Frères Jacqueline, König Peter, Schütt Olivier, Huch Volker, Blin Joël. 2005. Nanoscaled Sn and Pb particles aligned in Al2O3 tubes obtained from molecular precursors. European Journal of Inorganic Chemistry (18) : 3699-3710.

https://doi.org/10.1002/ejic.200500368

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Résumé : Tin and lead nanoparticles and metal sponges were prepared by reducing Me2Si(NtBu)2Sn (7) and Me2Si(NtBu)2Pb (9) with [H2AlOtBu] (3), [HAl(OtBu)2] (13), [H2AlOSiMe2tBu] (8), and [(Me2tBuSiO)2AlH] (15). Together with dihydrogen and the metals in their elemental state the monomeric compounds [Me2Si(NtBu)2Al(OSiMe2tBu)(THF)] (10) and [Me2-Si(NtBu)2Al(OtBu)(THF)] (11) can be obtained, to mention only two examples. Each monomer is stabilized by a THF molecule coordinated to aluminum, which on sublimation loses its donor molecule and dimerizes through Lewis acid-base interactions to the spiro compounds [Me2Si(NtBu)2AlO-SiMe2tBu]2 (12) and [Me2Si(NtBu)2AlOtBu]2 (4), respectively. The molecular structures of 10, 11, and 12 were determined by single-crystal X-ray diffraction techniques. The reduction of 7 at -115 °C is gradually indicated by a color change of the reaction mixtures from red to dark brown with increasing temperature and depending on the reducing agent used. The tin powders that were obtained were identified as ?-tin using X-ray powder diffraction techniques and their average crystallite size depends on the polarity of the solvent and hydride used. Under certain conditions metal sponges are formed. Pycnometric measurements were carried out on the tin and lead sponges. These showed almost the known densities for the metals when helium was used whereas significantly smaller ones were measured in water. Porous alumina membranes of different pore diameters were filled with tin and lead particles. Metal nanoparticles were prepared within the tubes of the membranes by reduction of the metal amides in the pores. The infiltration process can be repeated up to ten times increasing the amount of particles within the tubes monitored by SEM. The obtained brown or black membranes were characterized by SEM, EDX, and UV/Vis analysis. The filled membranes show sharp impervious ranges in the UV/ Vis spectrum between 270 and 525 nm and could therefore be used as wavelength filters.

Mots-clés Agrovoc : plomb, étain, élément métallique, nanotechnologie

Classification Agris : 000 - Autres thèmes

Champ stratégique Cirad : Hors axes (2005-2013)

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