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Thin-film growth of metallic platinum by aerosol-assisted chemical vapor deposition (AA-CVD) is an attractive alternative to the application of vacuum-based methods. This versatile and scalable technique allows gas phase deposition of thin-films from nebulized precursor solutions in a simple, open setup at moderate temperatures between 400 and 600°C. We discuss the film growth mechanisms on silicon and zirconia substrates in terms of microstructure, surface coverage, sheet resistance, and thermal stability. Furthermore, the positive influence of Pt thin-films deposited by AA-CVD on the area specific resistance (ASR) of symmetric Pt/YSZ/Pt cells in air is presented.

The ion conductivity of two series of porous ceramic diaphragms impregnated with caustic potash was investigated by electrochemical impedance spectroscopy. To understand the impact of the pore structure on ion conductivity, the three-dimensional (3-D) pore geometry of the diaphragms was characterized with synchrotron x-ray absorption tomography. Ion migration was calculated based on an extended pore structure model, which includes the electrolyte conductivity and geometric pore parameters, for example, tortuosity (τ) and constriction factor (β), but no fitting parameters. The calculated ion conductivities are in agreement with the data obtained from electrochemical measurements on the diaphragms. The geometric tortuosity was found to be nearly independent of porosity. Pore path constrictions diminish with increasing porosity. The lower constrictivity provides more pore space that can effectively be used for mass transport. Direct measurements from tomographs of tortuosity and constrictivity opens new possibilities to study pore structures and transport properties of porous materials.

Note: Times Cited: 10Si Reference EPFL-ARTICLE-206060doi:10.1002/fuce.200800116View record in Web of Science URL: ://WOS:000273394400015 Record created on 2015-03-03, modified on 2017-05-12

BaZr0.9Y0.1O3-δ has been synthesised by three different methods: the solid-state reaction, the spray pyrolysis and the spray drying. Significantly different apparent lattice parameters (between 0.4192 nm for the sample prepared by the solid-state reaction method and sintered at 1,500 °C and 0.4206 nm for the sample prepared by the solid-state reaction method and sintered at 1,720 °C) are observed after calcination and sintering, depending on the synthesis method and the sintering temperature. The bulk conductivity values also vary over several orders of magnitude (–7.2< log σb

Specific modification of properties such as porosity and pore size of engineered wood-based source material enables the custom design of porous wood-derived SiC that is produced by carbothermal reduction between the carbonized wood-based material and an infiltrated silica sol. In contrast to bulk wood, the anisotropic shrinkage of the source material is less distinctive and can be controlled. Furthermore, the obtained structural properties of the material are isotropic. Material processing and properties of the wood-derived ceramic material are described in this paper.

Solid oxide fuel cells are ceramic fuel cells that convert chemical into electrical energy at temperatures between 650 °C and 1000 °C. Today, this type of fuel cell is receiving ever-increasing attention due to its principle capability to provide electricity from both fossil and renewable fuel sources. Systems are currently under development for a variety of applications, including small and large-scale stationary combined heat and power systems, and power generation systems in the automotive area. Materials involved in advanced SOFC cells and their fabrication techniques are described in this contribution. The trends to enable lowering of the SOFC operating temperatures to around 800 °C and the resulting materials, as well as concept-related solutions, are addressed in particular.

A new method for transforming wood structures into ceramic by carbothermal reduction of silica and carbonized wood has been developed. Application of this technique allows the preservation of wood microstructures in the ceramic state and the conversion of wood components without constraints in component size. The chosen infiltration technique of silica sol incorporation into carbonized wood structures is examined in terms of sol and wood type, carbonization conditions of the wood,and thickness of the infiltrated carbon body. Ceramization conditions were optimized,and the reaction mechanism is discussed.

Solid oxide electrolyser cells (SOECs) have great potential for efficient and economical production of hydrogen fuel. Element diffusion between the Ni-cermet electrode and the metal substrate of metal supported cells (MSC) is a known problem in fuel cell and electrolysis technology. In order to hinder this unintentional mass transport, different ceramic diffusion barrier layers (DBLs) are included in recent cell design concepts. This paper is based on wavelength dispersive X-ray fluorescence investigations of different SOEC and focuses on Fe, Cr and Ni diffusion between the metal grains of the cathode and the metal substrate. Due to the low detection limits and therefore high analytical sensitivity, wavelength dispersive electron probe microanalysis (EPMA) provides a precise method to determine element distribution, absolute element concentration and changes between the reference material and aged cells on a microstructural level by element mappings and concentration profiles. The results of this work show considerable concentration gradients in the metal grains caused by mass exchange during cell operation. Diffusion can be inhibited significantly by integrating different ceramic DBLs of doped LaCrO3-type or doped LaMnO3-type perovskite, either by vacuum plasma spraying (VPS) or physical vapour deposition technique (PVD).