[en] Crumpled foils are a new type of material with promising characteristics due to their interesting mechanical properties associated with their low weight. They are fabricated by dye compaction, resulting in a structure consisting of randomly arranged ridges and vertices, thus providing a lot of self-contact. Mechanical properties and internal complex mesostructures were investigated using non-destructive techniques in order to link the microstructure to mechanical properties. As regards the mechanical characteristics, the influence of different parameters was studied: volume fraction of solid, loading–unloading cycle, simple or closed die compression, pre-folding of foils, compaction rate and creation of local welding. It appears possible to significantly change the mechanical behavior of crumpled foils, especially by increasing the solid fraction but also by generating the local welding of foils in the microstructure. A study of relaxation was also performed, which showed that these materials are slightly sensitive to deformation rate. Finally, a qualitative and quantitative study of the microstructure by in situ tests using X-ray tomography was conducted. This resulted in a better understanding of the behavior and local organization of foils during compaction

[en] We report here on the self-patterned growth of nanostructured epitaxial oxide thin films using a bottom-up approach. Different stepped (0001) sapphire surfaces have been used as templates to grow different nanostructured thin films of yttria-stabilized zirconia elaborated by a chemical solution deposition technique, namely sol-gel dip-coating. For such films, a morphological instability occurs during post-deposition thermal annealing that forces the film to split into isolated islands. Taking advantage of this effect, three distinct types of nanostructures have been produced depending on the step morphology of the substrate surface, and depending on the relative magnitude of the mean island diameter (D) and the mean terrace length (L). Flat-top islands, dome-shaped islands, tilted flat-top islands or self-organized arrays of nano-islands can be generated. Atomic force microscopy was used to observe nanostructures and quantitative characterizations of crystallographic and nanostructural aspects were carried out by high-resolution x-ray diffraction reciprocal space mapping