Assembly of 8YSZ nanoparticles into gas-tight 1-2 μm thick 8YSZ electrolyte layers using wet coating methods

The application of a thin film electrolyte layer with a thickness in the micrometer range could greatly improve current solid oxide fuel cells (SOFCs) in terms of operating temperature and power output. Since the achievable minimal layer thickness with conventional powder coating methods is limited to ∼5 μm, a variety of thin film methods have been studied, but results on regular large-scale anode substrates are still lacking in the literature. In this paper, a wet coating process is presented for fabricating gas-tight 1-2 μm thick 8YSZ electrolyte layers on a regular NiO/8YSZ substrate, with a rough surface, a high porosity and a large pore size. These layers were deposited in a similar way as conventional suspension based layers, but the essential difference includes the use of coating liquids (nano-dispersion, sol) with a considerably smaller particle size (85 nm, 60 nm, 35 nm, 6 nm). Successful deposition of such layers was accomplished by means of an innovative coating process, which involves the preparation of a hybrid polyvinyl alcohol/8YSZ membrane by dip-coating or spin-coating and subsequently burning out the polymer part at 500 °C. Results from He leak tests confirmed that the sintered layers posses a very low number of defects and with values in the range 10⁻⁴-10⁻⁶ (hPa dm³)/(s cm²) the gas-tightness of the thin film layers is satisfactory for fuel cell operation. Moreover, preliminary results have also indicated a potential reduction of the sintering temperature from 1400 °C to the range 1200-1300 °C, using the presented coating process.     

Optical interference coatings 2007 measurement problem

The 2007 Measurement Problem comprised measurements of the transmission and reflectance spectra and the determination of optical constants for a single oxide layer on fused silica. The angle of incidence was 45 degrees .     

Fabrication and characterization of three-dimensional InGaAs/GaAs nanosprings

This paper presents the use of a novel fabrication technique to produce three-dimensional (3D) nanostructures. The process is based on conventional microfabrication techniques to create a planar pattern in an InGaAs/GaAs bilayer that self-assembles into 3D structures during a wet etch release. The nanostructures are proposed to function as nanosprings for electromechanical sensors. Nanomanipulation inside a scanning electron microscope (SEM) was conducted to probe the structures for mechanical characterization. The results were validated by simulation.     

Storage ring free-electron lasing at 176 nm--dielectric mirror development for vacuum ultraviolet free-electron lasers

Mirrors for storage ring free-electron lasers in the vacuum ultraviolet must provide adequate reflectivity and resistance against synchrotron radiation. The free-electron laser system at ELETTRA (Trieste, Italy) is targeted to lase in the spectral range between 155 and 200 nm. It was demonstrated that dense oxide multilayer coatings allow lasing down to 189.9 nm. However, pure oxide systems show significant absorption at lower wavelengths and cannot be employed below 189.9 nm. Fluoride stacks can be deposited down to 130 nm with high reflection values above 95%, but their resistance against the harsh synchrotron environment is poor. They rapidly degrade; lasing cannot be realized with this mirror approach. For the range between 170 and 190 nm, hybrid systems--combining fluoride and oxide materials--have been manufactured. With appropriate deposition procedures, mirrors achieve reflectance values up to 99% and an adequate radiation resistance simultaneously. A mirror based on a conventional fluoride stack protected by a dense silicon dioxide protection layer was deposited and successfully employed for free-electron lasing at 176.4 nm.     

Landscape dynamics in Germany

Modern lifestyles, new demographic trends, and the expansion of the European Community are changing the European countryside. At stake are cultural landscapes, their richness in wildlife, historical interest, scenic beauty, and the recreational opportunities they provide. Visible phenomena of change are symptoms of a growing socio-economic and ecological disparity between different regions. Agreements on AGENDA 2000 European policy provide a new platform for regional and agricultural development. The paper explores which landscape dynamics are in store. Employing examples from rural Germany, the paper presents corridors of possible futures for unique, and at the same time, dynamic places. Modern strategies of landscape and urban planning are discussed which aim at closer co-operation between a multitude of stakeholders, policy makers, planners, and other agents of change. Methods and tools are needed to build consensus among ever increasing numbers of participants representing potentially wide ranges of values.     

High-K Dielectric Ceramics from Donor/Acceptor-Codoped (Ba1−xCax)(Ti1-yZry)O3 (BCTZ)

(Ba_{1− x} Ca _x )(Ti_{1− y} Zr _y )O₃ ceramics doped with various donors and acceptors were sintered in a reducing atmosphere and then annealed at different oxygen partial pressures. The dielectric maxima at the Curie point increased up to ∼30000 after reoxidation, depending on the grain size, the type of acceptor, and the annealing conditions. The increase of the dielectric maxima seems to be correlated with oxidation of the grain boundaries. The dielectric properties show relaxation effects with increased frequency.     

Untersuchungen zur Vergleichbarkeit der statischen und dynamischen Überdruckprüfung von druckfesten Kapselungen

Forschung im Ingenieurwesen - Der Einsatz von elektrischen Geräten in explosionsgefährdeten Bereichen erfordert besondere Schutzmaßnahmen, um eine Zündung der...     

Chinone. XIII. Synthese von 4,5,9,10-Tetrahydropyren-2,7-dion und Versuch zur Darstellung von Pyren-2,7-dion

Quinones. XIII. Synthesis of 4,5,9,10-Tetrahydropyrene-2,7-dione and Attempted Preparation of Pyrene-2,7-dione The titel quinones 7 and 9 are of interest as electron acceptors for organic conductors. The synthesis of their conjugate hydroquinones 6 and 8 via the metacyclophane derivative 3 is described. The tetrahydropyrene-2,7-dione 7 – obtained by oxidation of 6 – possesses only a limited stability, whereas pyrene-2,7-dion ( 9 ) proved to unstable to be isolated.