Nano Focus
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Epitaxially grown BZY films display high ionic conductivity
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esearch in the field of solid oxide fuel cells (SOFC) spans more than 20 years in an attempt to synthesize a cost-effective oxide material with high ionic conductivity at intermediate-tolow temperatures and good chemical stability, for a wide range of applications such as SOFCs for portable power supply in small electronic devices. High-temperature proton conductors, like yttrium-doped barium zirconate, are now considered as alternatives to the oxygen-ion conductor electrolytes conventionally used in SOFCs, which have been proven to be environmentally benign and efficient energy production devices. D. Pergolesi, E. Fabbri, and E. Traversa of the University of Rome ‘Tor Vergata’, Italy and the National Institute for Materials Science, Japan and their co-workers, fabricated grain-boundary– free thin films of yttrium-doped barium zirconate (BaZr0.8Y0.2O3-δ; BZY) that showed the highest proton conductivity ever reported under such a low temperature (350°C) for any oxide material. As reported in the September 19th issue of Nature Materials (DOI:10.1038/
Nano Focus Novel fabrication approaches yield continuous nanocomposite and nanoceramic fibers
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anoscale composite materials are being increasingly used as biomaterials, catalysts, sensors, energy-storage materials, filters, and in many other applications. There is need for improved methods to fabricate nanocomposites with better control and reproducibility of material properties including microstructure, chemistry, and dimensions that can also be applied to a wide variety of materials. Y. de Hazan of the Swiss Federal Laboratories for Materials Testing and Research (Empa), T. Graule of Empa and Technische Universitat
cells, at a temperature as low as 350°C (see figure). As seen in the figure, BZY film conductivity is significantly larger than best performing, stable oxygen-ion conductors used for SOFC applications in the intermediate temperature range. The researchers carried out an extensive in-plane x-ray diffraction analysis to confirm the crystalline nature of epitaxially grown BZY films and to obtain reciprocal space maps. The researchers used electrochemical impedance spectroscopy to carry out electrical analysis of BZY films grown on MgO substrate in the temperature range of 350°C to 650°C, in a humid atmosphere of 5% H2 in Ar. The proton conductivity of the BZY films grown on MgO substrate was measured to be about two orders of magnitude higher than sintered pellet of the same material. The researchers attribute the large proton conductivity observed in epitaxial films to the high crystalline nature of epitaxial films which minimizes nonconducting grain boundary regions. According to the researchers, the results from this study may open new perspectives in the development of miniaturized SOFCs for portable and low powerdemanding applications. Rohit Khanna
NMAT2837; p. 846), the researchers used pulsed laser deposition (PLD) to fabricate highly textured, epitaxially grown BZY films (1 µm thickness
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