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Université de Fribourg

Complementary techniques for solid oxide electrolysis cell characterisation at the micro- and nano-scale

Wiedenmann, Daniel ; Hauch, A. ; Grobéty, Bernard ; Mogensen, M. ; Vogt, U.F.

In: International Journal of Hydrogen Energy, 2009, p. -

High-temperature steam electrolysis by solid oxide electrolysis cells (SOEC) is a method with great potential for transforming clean and renewable energy from non-fossil sources to synthetic fuels such as hydrogen, methane or dimethyl ether, which have been identified as promising alternative energy carriers. With the same technology, fuel gas can be used in a very efficient way to reconvert...

Université de Fribourg

The transformation of synthetic hectorite in the presence of Cu(II)

Fischer, Håkon ; Weidler, Peter G. ; Grobéty, Bernard ; Luster, Jörg ; Gehring, Andreas U.

In: Clays and Clay Minerals, 2009, vol. 57, no. 2, p. 139-149

The influence of Cu(II) on the hydrothermal and thermal transformations of a synthetic hectorite was investigated by a combined approach using mainly X-ray diffraction, thermal analyses, and electron paramagnetic resonance spectroscopy. The presence of Cu(II) during hydrothermal treatment increased the crystallite size. Copper (II) was both structure-bound and associated with the inner surfaces...

Université de Fribourg

On source identification and alteration of single diesel and wood smoke soot particles in the atmosphere; an X-ray microspectroscopy study

Vernooij, Martine G. C. ; Mohr, M. ; Tzvetkov, G. ; Zelenay, V. ; Huthwelker, T. ; Kaegi, R. ; Gehrig, R. ; Grobéty, Bernard

In: Environmental Science and Technology, 2009, vol. 43, no. 14, p. 5339–5344

Diesel and wood combustion are major sources of carbonaceous particles in the atmosphere. It is very hard to distinguish between the two sources by looking at soot particle morphology, but clear differences in the chemical structure of single particles are revealed by C(1s) NEXAFS (near edge X-ray absorption fine structure) microspectroscopy. Soot from diesel combustion has a dominant spectral...

Université de Fribourg

WDX studies on ceramic diffusion barrier layers of metal supported SOECs

Wiedenmann, Daniel ; Vogt, U. F. ; Soltmann, C. ; Patz, O. ; Schiller, G. ; Grobéty, Bernard

In: Fuel Cells, 2009///doi: 10.1002/fuce.200800118

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...

Université de Fribourg

Activation mechanism and infiltration kinetic for pressureless melt infiltration of Ti activated Al₂O₃ preforms by high melting alloy

Vasi, Srdan ; Grobéty, Bernard ; Kuebler, Jakob ; Graule, Thomas

In: Advanced Engineering Materials, 2009, vol. 11, no. 8, p. 659 - 666

The infiltration mechanism of X3CrNi13-4 in titanium activated porous alumina preforms has been studied. Investigations revealed isolated steel-covered titanium particles beyond the infiltration front. The only transport path possible for the steel to form such wetted islands is through the gas phase. Supersaturation due to the mixing of the steel gas phase with the titanium rich gas phase...

Université de Fribourg

Synthesis of carbon nanotubes on La0.6Sr0.4CoO₃ as substrate

Thiele, Doreen ; Colmenarejo, E. Lopez-Camacho ; Grobéty, Bernard ; Züttel, Andreas

In: Diamond and Related Materials, 2009, vol. 18, no. 1, p. 34-38

A carbon nanotube/perovskite composite material was developed as material for air electrodes in fuel cells or zinc-air batteries. For this purpose, carbon nanotubes were directly grown on the perovskite La0.6Sr0.4CoO₃ impregnated with Fe solution which acted as substrate. The synthesis was carried out in a fluidised bed reactor. The carbon source was acetylene. The...

Université de Fribourg

CSL grain boundary distribution in alumina and zirconia ceramics

Vonlanthen, Pierre ; Grobéty, Bernard

In: Ceramics International, 2008, vol. 34, no. 6, p. 1459-1472

The distributions of general and coincidence site lattice (CSL) grain boundaries (GBs) in texture-free alumina and zirconia ceramics sintered at two different temperatures were investigated based on electron backscatter diffraction (EBSD) measurements. Results were compared with the distributions obtained from random 2D spatial models and with calculated random distributions reported in the...

Université de Fribourg

Seismic properties of the upper mantle beneath Lanzarote (Canary Islands): Model predictions based on texture measurements by EBSD

Vonlanthen, Pierre ; Kunze, Karsten ; Burlini, Luigi ; Grobéty, Bernard

In: Tectonophysics, 2006, vol. 428, no. 1-4, p. 65-85

We present a petrophysical analysis of upper mantle xenoliths, collected in the Quaternary alkali basalt fields (Series III and IV) from the island of Lanzarote. The samples consist of eight harzburgite and four dunite nodules, 5 to 15 cm in size, and exhibit a typical protogranular to porphyroclastic texture. An anomalous foliation resulting from strong recovery processes is observed in half of...

Université de Fribourg

Reaction-induced strain localization: torsion experiments on dolomite

Pianea, Claudio Delle ; Burlini, Luigi ; Grobéty, Bernard

In: Earth and Planetary Science Letters, 2007, vol. 256, no. 1-2, p. 36-46

We investigated the mechanical behaviour and microstructural evolution of a dolomite marble from Mt. Frerone (Adamello, N-Italy) during decarbonation to calcite and periclase in torsion experiments. Tests were performed in a Paterson gas-medium apparatus on cylindrical samples of 10 mm diameter and 10 mm length. Experiments were conducted at 800 °C, 300 MPa confining pressure under both vented...