Tetrapropylammonium (TPA)‐containing precursors are the building blocks in the crystallization of silica. In the first steps slab‐shaped silicalite nanoparticles are formed by ordered combination of the precursors (see picture). These nanoslabs have MFI‐type zeolite framework topology and play a key role in TPA‐ion‐mediated zeolite crystallization from monomeric and polymeric silica sources.

The fabrication of copper nanowires by electrodeposition in ion track membranes is reported. The large‐grain copper needle deposited at 40 °C shown in the Figure is a transition between the polycrystalline needles formed at room temperature and the single‐crystalline morphology at 60 °C. A systematic study of the DC deposition parameters required for single‐crystalline growth is presented.

13] The other two kinds of disordered solid state magnetic systems are the spin glasses and the amorphous magnets.The current industrial zeolite catalysts and adsorbent materials are physical mixtures of micrometer-sized, phasepure crystals shaped into larger bodies such as extrudates or granulates. There is considerable interest in the development of alternative zeolite catalysts and adsorbent materials (e.g., continuous zeolite films on dense or porous macroscopic supports including ceramic, metal, and poly(tetrafluoroethylene) (PTFE) modules, single-crystal wafers, and fibers). [1±14] A crucial aspect of zeolite films is their permeability, which is dependent on the orientation of the individual zeolite crystals that compose the film, with respect to the support. [3] In the work presented here, we have achieved oriented zeolite films of FAU structure±type on compositionally different, micrometer-sized EMT zeolite crystals, FAU and EMT being mnemonic codes for specific zeolite topologies. The possibility of overgrowing one zeolite phase with another opens perspectives for the development of polyfunctional zeolite materials with a controlled microscopic separation and organization of catalytic and/or adsorptive functions.The FAU and EMT zeolite topologies are structurally related. [15,16] These zeolite frameworks can be constructed by linking cubo-octahedra (sodalite units or b-cages) through hexagonal prisms into so-called faujasite sheets. Three different relative positions (a, b, and c) exist for these sheets, allowing linkage in the third crystallographic direction. Cubic stacking of faujasite sheets (abc) generates the FAU topology, whereas the hexagonal sequence (ab) gives rise to the EMT structure.The present FAU-on-EMT overgrowth material was achieved in a two-step synthesis procedure: Freshly prepared EMT zeolite crystals obtained by conventional crystallization [17] were dispersed into a synthesis gel for the FAU structure type. [18] The overgrowth was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 29 Si magic angle spinning nuclear magnetic resonance (MASNMR), and nitrogen adsorption techniques.The EMT support crystals were highly crystalline and phase±pure, as derived from the XRD pattern (Fig. 1a), SEM investigations (Fig. 2a) giving no evidence for the presence of another zeolite phase or residual gel, and nitrogen physisorption showing a micropore volume of 0.31 mL/ g, corresponding to the expected value. [18] The EMT crystals have the typical hexagonal-platelet morphology with diameters of 2 to 3 mm (Fig. 2b). Fig. 1. Powder XRD patterns of a) the EMT support crystals, b) the FAUon-EMT overgrowth material, and c) a pure FAU phase obtained in the absence of EMT support crystals [18]. The intensities of patterns a and c were scaled according to the relative proportions of the respective phases in the FAU-on-EMT overgrowth material.The presence of both the FAU and the EMT phases in the overgrowth sample is evidenced by XRD (...

Tetrapropylammonium(TPA)‐haltige Vorstufen sind die Bausteine bei der Silicalitkristallisation. In den ersten Schritten entstehen durch geordnete Zusammenlagerung der Vorstufen quaderförmige Silicalitnanopartikel (siehe Bild). Diese Nanoblöcke weisen die Topologie von Zeolith MFI auf und spielen eine Schlüsselrolle bei der TPA‐gesteuerten Kristallisation von Zeolithen ausgehend von mono‐ und polymeren Siliciumquellen.

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We have fabricated Pd/Ge/Au/Pt/Au ohmic contacts on n-type GaSb grown by molecular beam epitaxy. The annealed contacts show specific contact resistivities which are as low as 4.9×10−6 Ω−cm2 at an annealing temperature of 300 °C for 45 s. The resistivity is very sensitive to the annealing conditions and the thickness of the constituents. The surface remains smooth after annealing. Microstructure analysis with cross-sectional transmission electron microscopy and sputtered neutral mass spectrometry elucidates the solid phase reactions and interdiffusion of the constituents. The formation of a PdGe phase and the diffusion of Ge into GaSb seem to be the decisive and annealing-dependent processes leading to the ohmic behavior.

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