Science et Ingenierie des Materiaux et Procede s

Grenoble, France

Science et Ingenierie des Materiaux et Procede s

Grenoble, France
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Chalal M.,CNRS Physics Laboratory | Chalal M.,University of Science and Technology Houari Boumediene | Chalal M.,Université Ibn Tofail | Ehrburger-Dolle F.,CNRS Physics Laboratory | And 10 more authors.
Macromolecules | Year: 2010

The temperature-induced structural modifications of poly(N- isopropylacrylamide) hydrogel (pNIPA) were investigated by small-angle X-ray scattering (SAXS) over a broad range of q values (3.5 × 10-2-12 nm-1) at temperatures ranging between 18 and 37 °C. The sample studied was elaborated, by cryopolymerization yielding a macroporous gel (cryogel). The pNIPA gel forms the walls (the thickness at 23 °C is about 12 μm). The SAXS curves display an isoscattering (or isosbestic) point located at qiso = 3.633 nm-1 and disappearing above 30 °C. This feature has never been reported up to now. The SAXS curves obtained at each temperature are well fitted by a sum of four equations describing respectively the scattering resulting from the gel surface (power law), from the solidlike (Guinier equation) and liquidlike (Ornstein-Zernike equation) heterogeneities, and from the chain-chain correlation yielding a broad peak (pseudo-Voigt equation) in the high-q domain. The temperature dependence of the parameters obtained from the fit is analyzed and discussed. © 2010 American Chemical Society.


Latu-Romain L.,CNRS Microelectronics Technology Laboratory | Ollivier M.,CNRS Microelectronics Technology Laboratory | Ollivier M.,Stendhal University | Mantoux A.,Science et Ingenierie des Materiaux et Procede s | And 13 more authors.
Journal of Nanoparticle Research | Year: 2011

Si nanowires (NWs), with diameters of about 800 nm and lengths of about 10 μm, previously synthesized by the VLS method with gold catalyst, were carburized at 1,100 °C under methane for conversion into SiC nanostructures. These experiments have shown that Si NWs have been transformed into SiC nanotubes (NTs) with approximately the same sizes. Nanotubes' sidewall thickness varies from 20 to 150 nm depending on the NTs' height. These SiC nanotubes are hexagonal in shape and polycrystalline. A model of growth based on the out-diffusion of Si through the SiC layer was proposed to explain the transformation from Si nanowires to SiC nanotubes. This model was completed with thermodynamic calculations on the Si-H2-CH4-O2 system and with results from complementary experiment using propane precursor. Routes for obtaining crystalline SiC NTs using this reaction are proposed. © 2011 Springer Science+Business Media B.V.


Ollivier M.,CNRS Microelectronics Technology Laboratory | Ollivier M.,Stendhal University | Latu-Romain L.,CNRS Microelectronics Technology Laboratory | Martin M.,CNRS Microelectronics Technology Laboratory | And 6 more authors.
Journal of Crystal Growth | Year: 2013

The objective of this study is to grow Si-SiC core-shell nanowires (NWs) for bio-nano-sensors. The idea is to benefit from the electronic transport into the Si core NW and from the biocompatibility of the SiC shell all around the Si NW. Silicon nanowires (NWs) have been first obtained by a top-down approach. Before carburization, in situ deoxidation under H2 allowed significant smoothening and faceting of the Si NWs sidewalls. Then, Si NWs have been carburized under methane or propane at atmospheric pressure and at temperatures ≥ 1000 °C. Carburization of Si NWs leads to Si-SiC core-shell NWs with a thin (~3 nm), continuous and single crystalline cubic SiC shell. The 3C-SiC shell has been further thickened by chemical vapor deposition and preferential growth of 3C-SiC has been observed on the sidewalls of NWs. Based both on the electronic transport properties of silicon and on the biocompatibility of SiC, these new 1D-nanostructures could be an ideal object for nano-bio-sensors. © 2012 Elsevier B.V. All rights reserved.


Latu-Romain L.,CNRS Microelectronics Technology Laboratory | Ollivier M.,CNRS Microelectronics Technology Laboratory | Ollivier M.,Stendhal University | Thiney V.,Science et Ingenierie des Materiaux et Procede s | And 2 more authors.
Journal of Physics D: Applied Physics | Year: 2013

Because of their unique properties, silicon carbide nanotubes (SiC-NTs) have aroused particular research interest. In this letter, a new approach to fabricate SiC-NTs via the carburization of Si-NWs is presented. By controlling the pressure during the carburization process, out-diffusion of Si through the SiC layer can be monitored. Finally, 3C-SiC-NTs with faceted {2 0 0} sidewall planes are obtained with an excellent crystalline quality. The external diameter is about 300 nm (nearly the same than the etched Si-NWs used) and the thickness of the sidewalls is about 40-100 nm. The crystalline quality as well as the good reproducibility of the process may lead to various applications in physics, chemistry, energy storage and biology. © 2013 IOP Publishing Ltd.


Tian L.,Science et Ingenierie des Materiaux et Procede s | Giusti G.,Grenoble Institute of Technology | Soum-Glaude A.,CNRS PROMES | Dan C.Y.,Science et Ingenierie des Materiaux et Procede s | And 6 more authors.
Conference Record of the IEEE Photovoltaic Specialists Conference | Year: 2013

Nitrogen-doped TiO2 thin films were deposited by atomic layer deposition on glass substrates with various nitrogen concentrations for potential use in photovoltaic applications as a transparent p-type layer. Nitrogen doping was achieved by combining the use of titanium isopropoxide, N2O and NH3 as precursors. All the films were deposited at 265°C. The maximum nitrogen doping level achieved in this study was 4.5 at. % resulting in films exhibiting a resistivity of 116 Ω cm associated with an average transmittance of 65% in the visible-infrared range. © 2013 IEEE.


Ollivier M.,CNRS Laboratory for Microelectronics Technolgy | Ollivier M.,Stendhal University | Latu-Romain L.,CNRS Laboratory for Microelectronics Technolgy | Bano E.,Stendhal University | And 2 more authors.
Materials Science Forum | Year: 2012

Carburization of silicon nanowires (NWs), with diameters of about 800 nm and lengths of about 10 μm, under methane at high temperature in order to obtain silicon carbide (SiC) nanostructures is reported here. The produced SiC nanostructures display a tubular shape and are polycrystalline. The as-prepared silicon carbide nanotubes (NTs) were characterized and studied by scanning electron microscopy (SEM), dual focused ion beam - scanning electron microscope (FIB-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The formation of nanotubes can be explained by the out-diffusion of Si through the SiC during the carburization process. © (2012) Trans Tech Publications.


Ollivier M.,CNRS Laboratory for Microelectronics Technolgy | Ollivier M.,Stendhal University | Latu-Romain L.,CNRS Laboratory for Microelectronics Technolgy | Mantoux A.,Science et Ingenierie des Materiaux et Procede s | And 2 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2011

We report the elaboration of silicon carbide (SiC) nanostructures thanks to the carburization of silicon microwires (MWs) under methane at high temperature. The produced SiC nanostructures display a tubular shape and are polycrystalline. The as-prepared silicon carbide microtubes (MTs) were characterized and studied by scanning electron microscopy (SEM), dual focused ion beam- scanning electron microscope (FIB-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The formation of microtubes can be explained by the out-diffusion of Si through the SiC during the carburization process. Copyright © 2011 American Scientific Publishers All rights reserved.

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