The fabrication of nanoscopic silicon based membranes has been carried out by using a non‐expensive electrochemical preparation technique. For these purposes an n+‐silicon wafer is anodized to create oriented pores with typical diameters around 50 nm. The length of the channels is up to 50 μm which yields to an aspect ratio of 1000. The channels of these templates are partially filled with a metal, especially a ferromagnetic one to obtain an array of nanostructures. Metal‐deposition within such high aspect ratio pores is a great challenge but could be realized in some extent. The introduced silicon based nanocomposite offers the opportunity to change between different nano‐architectures by accurate adjustment of the electrochemical fabrication parameters. Also the size and spatial distribution of the precipitated metal‐structures within the pores can be varied by altering the galvanic deposition process. Different morphologies and varying metal fillings modify the physical properties (e.g. magnetic behaviour) of the nanocomposite system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Cubic Li 7 La 3 Zr 2 O 12 (LLZO), stabilized by supervalent cations, is one of the most promising oxide electrolyte to realize inherently safe all-solid-state batteries. It is of great interest to evaluate the strategy of supervalent stabilization in similar compounds and to describe its effect on ionic bulk conductivity σ′ bulk . Here, we synthesized solid solutions of Li 7– x La 3 M 2– x Ta x O 12 with M = Hf, Sn over the full compositional range ( x = 0, 0.25...2). It turned out that Ta contents at x of 0.25 (M = Hf, LLHTO) and 0.5 (M = Sn, LLSTO) are necessary to yield phase pure cubic Li 7– x La 3 M 2– x Ta x O 12 . The maximum in total conductivity for LLHTO (2 × 10 –4 S cm –1 ) is achieved for x = 1.0; the associated activation energy is 0.46 eV. At x = 0.5 and x = 1.0, we observe two conductivity anomalies that are qualitatively in agreement with the rule of Meyer and Neldel. For LLSTO, at x = 0.75 the conductivity σ′ bulk turned out to be 7.94 × 10 –5 S cm –1 (0.46 eV); the almost monotonic decrease of ion bulk conductivity from x = 0.75 to x = 2 in this series is in line with Meyer–Neldel’s compensation behavior showing that a decrease in E a is accompanied by a decrease of the Arrhenius prefactor. Altogether, the system might serve as an attractive alternative to Al-stabilized (or Ga-stabilized) Li 7 La 3 Zr 2 O 12 as LLHTO is also anticipated to be highly stable against Li metal.

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Self‐assembled porous media with a quasi‐regular structure offer the possibility to arrange nanoparticles/nanowires in three dimensions. The regular pore‐patterns of the matrix can be achieved in a certain regime, ranging between pore‐diameters of 40 nm up to 100 nm using the same doping density of the silicon substrate. Furthermore the formation of a double‐sided porous layer with a thickness of 30 µm on each side was obtained. These porous silicon membranes with rather regular pore‐arrangements, even fabricated double‐sided, are filled with Ni during electrolytic deposition. The precipitation is performed in using a metal salt solution which is reduced in a cathodic process. The achieved nanocomposite can be varied on the one hand by modification of the nano‐architecture of the silicon template and on the other hand by altering the metal deposition process. Structural characterization of the template and of the deposited metal is performed by scanning electron microscopy, especially by recording the back scattered electrons. EDX‐mapping is performed in order to get chemical information. Different specimens exhibiting various pore‐arrangements and different Ni‐loadings with structures of distinct shape (spheres up to wires) show specific magnetic properties. A relation between the structure and magnetic characteristics is established. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Nanoporous gold (np-Au), produced by dealloying in silver nitrate solution exhibits extraordinary high surface-to-volume ratios of more than 20 m 2 /g which represents an excellent prerequisite for property tuning by surface charging. Upon electrochemical charging in aqueous KOH solution, the electrical resistance is observed to vary reversibly by up to 88%. The charge coefficient, thus the sensitivity of the resistance toward the imposed charge per mol, is however significantly smaller compared to conventionally prepared np-Au, etched in nitric acid solution. While the strong resistance variation observed in the present work can directly be related to the high charge transfer due to extraordinary fine porosity, the charge coefficients can be understood with regards to the matrix resistance of the respective materials, which is strongly influenced by dealloying residuals.

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