Oxide glasses are an integral part of the modern world, but their usefulness can be limited by their characteristic brittleness at room temperature. We show that amorphous aluminum oxide can permanently deform without fracture at room temperature and high strain rate by a viscous creep mechanism. These thin-films can reach flow stress at room temperature and can flow plastically up to a total elongation of 100%, provided that the material is dense and free of geometrical flaws. Our study demonstrates a much higher ductility for an amorphous oxide at low temperature than previous observations. This discovery may facilitate the realization of damage-tolerant glass materials that contribute in new ways, with the potential to improve the mechanical resistance and reliability of applications such as electronic devices and batteries.

Polymer-layered silicate nanocomposites have drawn a great interest in polymer science these past years. Understanding of the complex mechanism of dispersion and exfoliation of the clay tactoids may allow us to better control the final morphology and the homogeneity of clay nanocomposites and thus their macroscopic properties. The first step we propose in this study consists of a multiscale approach of the exfoliation state of the extruded polypropylene/montmorillonite nanocomposite. We used three extruders designs: a single-screw extruder, a twin-screw extruder, and an optimized-screw extruder with adapted shear. The rheological analysis, the WAXS diffractograms, and the TEM micrographs all show different nanocomposite morphologies. A statistical TEM image analysis methodology was developed to evaluate the different particle parameters (thickness, length, aspect ratio, interparticle distance). The results obtained show a correlation between the size of the tactoids and the shear intensity.

Pulsed laser ablation has proved its reliability for the synthesis of nano-particles and nano-structured materials, including metastable phases and complex stoichiometries. The possible nucleation of the nanoparticles in the gas phase and their growth has been little investigated, due to the difficulty of following the gas composition as well as the thermodynamic parameters. We show that such information can be obtained from the optically active plasma during its short lifetime, only a few microseconds for each laser pulse, as a result of a quick quenching due to the liquid environment. For this purpose, we follow the laser ablation of an α-Al2O3 target (corindon) in water, which leads to the synthesis of nanoparticles of γ-Al2O3. The AlO blue-green emission and the Al(I) (2)P(0)-(2)S doublet emission provide the electron density, the density ratio between the Al atoms and AlO molecules, and the rotational and vibrational temperatures of the AlO molecules. These diagnostic considerations are discussed in the framework of theoretical studies from the literature (density functional theory). We have found that starting from a hot atomized gas, the nucleation cannot occur in the first microseconds. We also raise the question of the influence of water on the control of the stoichiometry.

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We performed laser ablation of doped oxides, Y 2 O 3 :-Eu 3þ , Gd 2 O 3 :Eu 3þ , and Y 3 Al 5 O 12 :Ce 3þ (YAG:Ce), in an aqueous solution of 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEEAA). Nanoparticles are produced and characterized using electron microscopy and luminescence spectroscopy. We show that the polyether chain ensures the stabilization of the objects formed in aqueous medium while the complexing group limits their size and sharpens the size distribution. The nanoparticles produced from the sesquioxide targets are in a "cubic disordered" phase as expected for very small particles. The ablation of the YAG target leads to a majority of R-Al 2 O 3 and YAG nanoparticles and a minority of YAlO 3 nanoparticles. Infrared spectroscopy is used to characterize the nature of the complex formed between the ligand and the particle surface. We demonstrate that the coordination mode of the carboxylate (-COO -) group to metal ions of the nanoparticles' surface is the bridging bidentate mode.

The mechanical behavior of h1 0 0i-oriented MgO nanocubes is investigated using in situ transmission electron microscopy (TEM) compression tests at room temperature and molecular dynamics simulations. Experiments show high strength and ductility, in addition to specific deformation mechanisms interpreted by the simulation. The nucleation and the propagation of 1/2h1 1 0i{1 1 0} dislocations are at the onset of the plastic deformation. The different deformation processes as well as the possible formation of a dislocation network during compression are discussed.

This paper demonstrates the usefulness of pulsed laser ablation in liquids as a fast screening synthesis method able to prepare even complex compositions at the nanoscale. Nanoparticles of Y2O3:Eu3+, Lu2O2S:Eu3+, Gd2SiO5:Ce3+, Lu3TaO7:Gd3+ and Tb3+ are successfully synthesized by pulsed laser ablation in liquids. The phase and stoichiometries of the original materials are preserved while the sizes are reduced down to 5-10 nm. The optical properties of the materials are also preserved but show some small variations and some additional structures which are attributed to the specificities of the nanoscale (internal pressure, inhomogeneous broadening, surface states, etc).

Intercalated and exfoliated nanocomposites were prepared by extrusion and injection of polyamide‐6 and highly swollen or slightly swollen montmorillonite, respectively. The microstructure of the nanocomposites has been studied previously. In this article, we investigated the influence of the preferential orientation of the montmorillonite sheets on the mechanical properties of the nanocomposites. Dynamic mechanical analysis and tensile tests showed that the elastic modulus depends mainly on the filler loading. A parallel coupling could well account for the behavior of the nanocomposites. The calculated elastic and storage moduli of montmorillonite were set to 140 and 40 GPa, respectively. Compression tests were performed to study the anisotropy of the mechanical properties. The elastic modulus and flow strain were sensitive to the filler orientation. A Tandon–Weng approach was applied to consider the geometry of the filler. In all low‐deformation tests, no significant difference between intercalated and exfoliated systems was observed. Finally, the influence of the dispersion and exfoliation state of the filler on the ultimate properties of the nanocomposites (tensile tests) is discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 272–283, 2002