FLUX DENSITY GRADIENTS IN PLASTICALLY DEFORMED NIOBIUM SINGLE CRYSTALS

En utilisant l'effet magnéto-optique de Faraday, nous avons analysé la pénétration de la phase de Shubnikov dans des monocristaux de niobium déformés plastiquement. L'anisotropie de l'interaction entre les vortex et l'arrangement des dislocations conduit à une pénétration du flux fortement anisotrope. Une détermination quantitative du profil de l'induction magnétique nous a permis de déterminer les gradients locaux de l'induction et des forces d'ancrage des vortex.By means of the Faraday magneto-optical technique the penetration of the Shubnikov phase into plastically deformed niobium single crystals was analysed. The anisotropy of the interaction between the flux line lattice and the dislocation arrangements leads to an strongly anisotropic flux penetration. By a calibration of the flux density it was possible to determine the local flux density gradients and pinning forces

THE MICROSTRUCTURE OF METAL-OXIDE BOUNDARIES

Al and Au have been coated (electron-beam deposition) onto (001) MgO, and polycrystalline Ni has been solid state bonded onto (001) MgO for the study of the physics and chemistry of metal-oxide boundaries. These boundaries were characterized by conventional -, analytical- and high resolution transmission electron microscopy (HREM). The observed microstructures are discussed with reference to the O-lattice theory, DSC-theory, Image Force Theorem, thermodynamics and kinetics of such boundaries