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There is a great interest to synthesize ferroelectric ceramics both with fine grain size and significant electric properties. Here, we report the preparation of nanostructured tetragonal barium titanate by combining forced hydrolysis of metallic salts in polyol, soft annealing and 650 °C spark plasma sintering under uniaxial pressure of 120 MPa for 5 min. The stabilization of highly dense (density of 90%), nanostructured (grains about 50 nm) tetragonal barium titanate ceramic was achieved. The produced ceramic exhibited ferroelectric behavior and a dielectric permittivity of 3600 at 1 kHz and room temperature. [ABSTRACT FROM AUTHOR]

Polyol Process Coupled to Cold Plasma as a New and Efficient Nanohydride Processing Method: Nano-Ni2H as a Case Study. In the last paragraph of Section 3 - Results and Discussion, the sentence "Within relatively soft operating conditions almost pure granular Ni SB 2 sb H hydrides are produced reaching a hydrogen storage capacity of 1.7 wt %" should be "Within relatively soft operating conditions almost pure granular Ni SB 2 sb H hydrides are produced reaching a hydrogen storage capacity of 0.9 wt %". In Section 4 - Conclusions, the sentence "By this material processing route, a hydrogen storage capacity of 1.7 wt % was reached" should be "By this material processing route, a hydrogen storage capacity of 0.9 wt % was reached". [Extracted from the article]

Replacing materials based on rare-earth elements in current permanent magnets is a real scientific, economic and environmental challenge. Ferromagnetic 3d transition metals seem an apt direction to go in this field, due to their high residual magnetization and thermal stability. In order to improve their coercive behavior, nanostructured magnets based on the assembly of high-aspect-ratio nanoparticles ( i.e. cobalt based nanorods and nanowires) have recently been proposed. In these, the nanoparticle morphology itself drives the magnetization reversal mechanism. This purely geometrical effect seems to obscure the effects of structural defects, although it is clear that high magnetocrystalline energy is required to maintain a stable orientation of the magnetic moment inside the nanoparticles. We present here an experimental study whose aim is to distinguish the role of the stacking faults from the effects of shape and morphology on the magnetization reversal mechanism in cobalt-based nanowires. Coercive field results have been obtained on Co 80 Ni 20 nanowires synthesized by a polyol process. Through accurate control of shape and morphology, it was possible to discard the effects of shape and thus to highlight the influence of crystal defects on the magnetism of Co 80 Ni 20 nanowires. A micromagnetic study, consistent with the experimental analyses, is also presented. The results discussed in this work clearly show that even if the morphological characteristics are conducive to a high coercive field, the presence of numerous stacking faults has the opposite effect and leads to materials with a significantly lower coercive field than expected, which is not suitable for permanent magnet applications. [ABSTRACT FROM AUTHOR]

A R&D program is developed at the ALTO facility to provide new beams of exotic neutron-rich nuclei, as intense as possible. In the framework of European projects, it has been shown that the use of refractory targets with nanometric structure allows us to obtain beams of nuclei unreachable until now. The first parameter to be controlled in the processing to obtain targets with a homogeneous nanostructure is the grinding of uranium dioxide, down to 100 nm grain size. In this study, dry and wet grinding routes are studied and the powders are analyzed in terms of phase stabilization, specific surface area and grain morphology. It appears that the grinding, as well dry as wet, leads to the decrease of the particle size. The oxidation of UO 2 is observed whatever the grinding. However, the dry grinding is the most efficient and leads to the oxidation of UO 2 into U 4 O 9 and U 3 O 7 whose quantities increase with the grinding time while crystallite sizes decrease. [ABSTRACT FROM AUTHOR]

Review: 40 refs. [ABSTRACT FROM AUTHOR]