Mismatch Strain versus Dangling Bonds: Formation of "Coin-Roll Nanowires" by Stacking Nanosheets

(Figure Presented) The third dimension comes to the rescue in the synthesis of laterally confined 2D crystals. Graphene-type sheets of layered metal(IV) chalcogenides are stabilized by stacking to form nano-objects that resemble a coin roll. Mismatch strain between NbS2 and WS2 lattices is important for the stabilization of the coin-roll structure as well as for preventing the formation of the intrinsically more stable scroll structures such as fullerenes or nanotubes. © 2010 Wiley-VCH Verlag GmbH &. Co. KGaA

Synthesis of Fullerene- and Nanotube-Like SnS2 Nanoparticles and Sn/S/Carbon Nanocomposites

SnS2 nested fullerene-type (IF) nanoparticles, nanotubes, and SnS2/C hybrid nanostructures were obtained by vapor transport starting from elemental tin and CS2. The reaction was carried out in a single-step process by heating elemental tin metal powder in a horizontal tube furnace at 800-1000 degrees C. TEM analysis allowed proposing a plausible mechanism for the formation of fullerene-like particles of SnS2 as well as tubes and scrolls from nanosheets of SnS2. Pure material could be obtained by optimizing the reaction based on a product analysis using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX). RI Kolb, Ute/A-2642-2011; Tremel, Wolfgang/D-8125-2011; Mugnaioli, Enrico/E-6237-201

Solution Synthesis of a New Thermoelectric Zn1-xSb Nanophase and Its Structure Determination Using Automated Electron Diffraction Tomography

Engineering materials with specific physical properties have recently focused on the effect of nanoscopic inhomogeneities at the 10 nm scale. Such features are expected to scatter medium- and long-wavelength phonons thereby lowering the thermal conductivity of the system. Low thermal conductivity is a prerequisite for effective thermoelectric materials, and the challenge is to limit the transport of heat by phonons, without simultaneously decreasing charge transport. A solution-phase technique was devised for synthesis of thermoelectric "Zn4Sb3" nanocrystals as a precursor for phase segregation into ZnSb and a new Zn-Sb intermetallic phase, Zn1+delta Sb, in a peritectoid reaction. Our approach uses activated metal nanoparticles as precursors for the synthesis of this intermetallic compound. The small particle size of the reactants ensures minimum diffusion paths, low activation barriers, and low reaction temperatures, thereby eliminating solid-solid diffusion as the rate-limiting step in conventional bulk-scale solid-state synthesis. Both phases were identified and structurally characterized by automated electron diffraction tomography combined with precession electron diffraction. An ab initio structure solution based on electron diffraction data revealed two different phases. The new pseudo-hexagonal phase, Zn1+delta Sb, was identified and classified within the structural diversity of the Zn-Sb phase diagram. RI Kolb, Ute/A-2642-2011; Birkel, Christina/D-6144-2011; Tremel, Wolfgang/D-8125-2011; Mugnaioli, Enrico/E-6237-201

Synthesis of Fullerene- and Nanotube-Like SnS2 Nanoparticles and Sn/S/Carbon Nanocomposites

SnS 2 nested fullerene-type (IF) nanoparticles, nanotubes, and SnS 2/C hybrid nanostructures were obtained by vapor transport starting from elemental tin and CS 2. The reaction was carried out in a single-step process by heating elemental tin metal powder in a horizontal tube furnace at 800-1000 ° C. TEM analysis allowed proposing a plausible mechanism for the formation of fullerene-like particles of SnS 2 as well as tubes and scrolls from nanosheets of SnS 2. Pure material could be obtained by optimizing the reaction based on a product analysis using powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) combined with energy-dispersive X-ray spectroscopy (EDX). © 2009 American Chemical Society

Solution Synthesis of a New Thermoelectric Zn1-xSb Nanophase and Its Structure Determination Using Automated Electron Diffraction Tomography

Engineering materials with specific physical properties have recently focused on the effect of nanoscopic inhomogeneities at the 10 nm scale. Such features are expected to scatter medium- and long-wavelength phonons thereby lowering the thermal conductivity of the system. Low thermal conductivity is a prerequisite for effective thermoelectric materials, and the challenge is to limit the transport of heat by phonons, without simultaneously decreasing charge transport. A solution-phase technique was devised for synthesis of thermoelectric "Zn(4)Sb(3)" nanocrystals as a precursor for phase segregation into ZnSb and a new Zn-Sb intermetallic phase, Zn(1+delta)Sb, in a peritectoid reaction. Our approach uses activated metal nanoparticles as precursors for the synthesis of this intermetallic compound. The small particle size of the reactants ensures minimum diffusion paths, low activation barriers, and low reaction temperatures, thereby eliminating solid-solid diffusion as the rate-limiting step in conventional bulk-scale solid-state synthesis. Both phases were identified and structurally characterized by automated electron diffraction tomography combined with precession electron diffraction. An ab initio structure solution based on electron diffraction data revealed two different phases. The new pseudo-hexagonal phase, Zn(1+delta)Sb, was identified and classified within the structural diversity of the Zn-Sb phase diagram

Bismuth-Catalyzed Growth of SnS2 Nanotubes and Their Stability

Nanotubes of tin disulfide were fabricated from SnS2 nanoflakes by the vapor-liquid-solid process using bismuth nanodroplets as a catalyst. The SnS2 reagent in the gas phase preferentially adsorbs onto the bismuth particles; upon cooling, nucleation and growth of SnS2 nanotubes occurs (see HRTEM image). Annealing the nanotubes results in the formation of SnS 2/SnS superlattices. © 2009 Wiley-VCH Verlag GmbH & Co. KCaA