LISM

Witry-lès-Reims, France
Witry-lès-Reims, France
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PubMed | University of Sfax and LISM
Type: | Journal: Journal of microscopy | Year: 2016

For studying the electrical properties (charge trapping, transport and secondary electron emission) of the polypropylene-based nanocomposites with different contents of natural clay, the specimens were submitted to electron irradiation of a scanning electron microscope. A device, suitably mounted on the sample holder of the scanning electron microscope, was used to measure two currents (i.e. leakage and displacement currents) induced in the polypropylene-based nanocomposites (polymer nanocomposites) under electron irradiation. The evolution of trapped charge during irradiation for each type of studied polymer nanocomposites is deduced. The amount of trapped charge at the steady state is also determined by measuring the change of secondary electron image size associated to the electron trajectory simulation. It is found, surprisingly, that not only the leakage current increases as a function of clay loading level but also trapped charge. However, this could be related to the increase of conductivity in one hand and to proliferation of interfaces between nanoparticles and neighbouring materials on the other hand. These two processes play crucial role in controlling the carrier transport (through polymer nanocomposites or/and along its surface) closely related to the charge storage and leakage current. Additional experiment using dielectric spectroscopy were performed to show the effect of clay concentration in changing the dielectric relaxation behaviour and to evidence the existence of interfaces between nanoparticles and polymer. The secondary electron emission during electron irradiation is also studied through the total electron yield that is deduced by correlating the measured leakage and displacement currents.


Drevet R.,L.I.S.M. | Nzoghe-Mendome L.,L. M. E. N. EA 3799 | Benhayoune H.,L.I.S.M. | Ebothe J.,L. M. E. N. EA 3799
Journal of Nanoscience and Nanotechnology | Year: 2012

Nanoscale surface modification of Ti6Al4V prosthetic material was investigated at 37 °C into a physiological liquid named Ringer's solution. The root-mean-square surface roughness evolution of the material as a function of immersion time was evaluated by atomic force microscopy (AFM) and 3D reconstruction of scanning electron microscope images (SEM). The results obtained from both techniques clearly showed a decrease of the root-mean-square surface roughness during the first 6 hours of immersion in the physiological liquid that is followed by a stability of the roughness value at longer durations. Moreover, the study of the roughness parameters extracted from AFM measurements is used to explain the smoothing process occurring at the interface between the prosthetic material and the physiological liquid. Copyright © 2012 American Scientific Publishers All rights reserved.


Dubois M.,LISM | Brown D.,Los Alamos National Laboratory | Clausen B.,Los Alamos National Laboratory | Addad A.,Lille University of Science and Technology | Lodini A.,LISM
Solid State Phenomena | Year: 2014

The aim of this work is to understand the evolutions of the β1 metastable austenite phase of a CuAlBe Shape Memory Alloy at macroscopic and microscopic scales under mechanical solicitation by neutron diffraction. The tensile specimen, taken in the raw material is subjected to superelastic cycles at room temperature on SMARTS diffractometer. Before loading, the mater ial is fully austenitic. During loading, after elastic deformation of austenite, phase transformation starts, martensite variants appear. The material follows a law of pseudo elastic behavior. At the end of the first mechanical cycle after unloading, the macroscopic curve does not fully return into its original point. A macroscopic deformation is observed. The evolution of first order microdeformations during mechanical cycles shows a large deformation of (400) plane family. This deformation is linked to the presence of <001> partial fibber characterizing the crystallographic texture of the material after elaboration. The FWHM of the (400) diffraction peak is also largely increased during loading. This increase is the signature of the generation of stacking faults during the transformation of β1 metastable austenite into β1 martensite. © (2014) Trans Tech Publications, Switzerland.


Rousse C.,LISM | Beaufils S.,LISM | Fricoteaux P.,LISM
Electrochimica Acta | Year: 2013

The electrosynthesis of Cu, Zn and Cu-Zn deposits from the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid has been investigated. Anion of this metallic salt (bis(trifluoromethylsulfonyl) imide) is the same as that used as the solvent. The redox potential sequence of copper and zinc in the used ionic liquid was the same as that of aqueous solvent. The obtained voltammograms for single metal deposition exhibits several electrodeposition steps. In the case of copper, the first step does not lead to metal deposition and is attributed to the Cu(II) → Cu(I) transformation. Rest of the steps result in the Cu(O). Contrary, all the steps in zinc deposition, correspond to growth of metallic deposits. In the case of the copper-zinc alloys, their chemical composition exhibits a surprising evolution versus potential and seems to be greatly dependent on the cathodic steps. The morphology and analysis of copper, zinc and their alloys are reported. © 2013 Elsevier Ltd. All rights reserved.


PubMed | L.I.S.M.
Type: Journal Article | Journal: Journal of nanoscience and nanotechnology | Year: 2012

Nanoscale surface modification of Ti6Al4V prosthetic material was investigated at 37 degrees C into a physiological liquid named Ringers solution. The root-mean-square surface roughness evolution of the material as a function of immersion time was evaluated by atomic force microscopy (AFM) and 3D reconstruction of scanning electron microscope images (SEM). The results obtained from both techniques clearly showed a decrease of the root-mean-square surface roughness during the first 6 hours of immersion in the physiological liquid that is followed by a stability of the roughness value at longer durations. Moreover, the study of the roughness parameters extracted from AFM measurements is used to explain the smoothing process occurring at the interface between the prosthetic material and the physiological liquid.


Fricoteaux P.,LISM | Rousse C.,LISM
Journal of Electroanalytical Chemistry | Year: 2014

The electrosynthesis of Cu-Zn, Al and Cu-Zn-Al nanowires from the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid was investigated. The anion of the metallic salts was the same as the solvent, i.e. bis(trifluoromethylsulfonyl)imide. The electrodeposition mechanism of each individual metal is complicated and shows many cathodic stages. The arrangement of these different steps in the current density-potential curves of alloys leads to unexpected composition evolution of deposits versus potential. According to the applied polarisation, a wide range of alloy compositions can be obtained. © 2014 Elsevier B.V. All rights reserved.

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