Laboratoire d’analyse et d’architecture des systèmes
A.NICOLLET, S.CHARLOT, V.BAIJOT, A.ESTEVE, C.ROSSI
Rapport LAAS N°17156, Août 2017, 1p.
Y.GAO, L.MARIN MERCADO, E.C.MATTSON, J.CURE, C.E.NANAYAKKARA, J.F.VEYAN, A.LUCERO, J.KIM, C.ROSSI, A.ESTEVE, Y.J.CHABAL
University of Texas, NEO
Revue Scientifique : Journal of Physical Chemistry C, Vol.121, N°23, pp.12780-12788, Juin 2017, DOI: 10.1021/acs.jpcc.7b02661 , N° 17098
Deposition of Al on ZnO is used for a number of electronic and catalytic devices as well as for nanoenergetic materials. The interface structure and chemical composition often control the performance of devices. In this study, in situ infrared spectroscopy, X-ray photoemission spectroscopy, and low energy ion scattering are combined to investigate the initial stage of interface formation between Al and ZnO. We find that (a) the interface is highly inhomogeneous with discontinuous Al patches, leaving ∼10% of the ZnO surface uncovered even after deposition of an equivalent of 11 nm-thick Al film; (b) upon Al deposition, Al reduces ZnO by forming Al2O3 and releasing Zn to the surface, and this process continues as more Al is deposited; (c) the reduced surface Zn atoms readily desorb at 150 °C; and (d) at higher temperature (>600 °C) all Al is oxidized as a result of mass transport. Deposition of a thin Al2O3 layer on ZnO prior to Al deposition effectively prevents Al penetration and Zn release, requiring higher temperatures to oxidize Al.
V.BAIJOT, M.DJAFARI ROUHANI, C.ROSSI, A.ESTEVE
Revue Scientifique : Combustion and Flame, Vol.180, pp.10-19, Juin 2017 , N° 16410
This paper presents a hierarchical multiscale approach based on a micro-kinetic model enabling to predict temperature, pressure and species generated during the thermite reaction of Al nanoparticles mixed with CuO nanoparticles. Overall, our phenomenological model integrates and combines series of complex atomistic mechanisms, e.g. diffusion and phase transformation, gas phase reactions and interphase exchange mechanisms, in particular molecular condensation, evaporation and decomposition. Thermodynamics considerations as well as Density Functional Theory (DFT) calculations are used to implement rate equations expressing the complex reactions at solid/liquid/gas interphases. We demonstrate that the model can predict the pressure–time dependence, the different phases and compositions with good accuracy at significantly low computational cost. The influence of Al and CuO particle size, compaction or density, alumina shell thickness and stoichiometry on the pressure and temperature versus time is theoretically predicted with fairly good agreement with available experimental data. A maximum pressure of 47 MPa and adiabatic temperature of 3500 K are obtained at high compaction, i.e. 50% of the TMD (Theoretical Maximum Density) for stoichiometric mixture, where AlO is shown to be the prevailing gaseous species. At low compaction, we highlight the role of ambient oxygen condition for which the model gives a maximal pressure of 4.2 MPa for Al rich mixtures (stoichiometric ratio of 1.2).
A.DANGERFIELD, C.E.NANAYAKKARA, A.MALLIKARJUNAN, X.LEI, R.M.PEARLSTEIN, A.DERECSKEI-KOVACS, J.CURE, A.ESTEVE, Y.J.CHABAL
University of Texas, Versum Materials Inc, NEO
Rapport LAAS N°17137, DOI: 10.1021/acs.chemmater.7b01816, Juin 2017, 11p.
Aminosilanes are attractive precursors for atomic layer deposition of silicon oxides and nitrides because they are halide-free and more reactive than chlorosilanes. However, the deposition of silicon nitride on oxide substrates still requires relatively high temperatures. We show here that for a process involving disec-butylaminosilane and hydrazine, the insertion of Al from trimethyl aluminum allows the deposition of silicon nitride films at relatively low temperatures (250 °C). First-principles calculations reveal that the presence of Al increases the binding of molecular hydrazine, thereby effectively enhancing the reactivity of hydrazine with the silicon precursor during the atomic layer deposition process, which leads to nitrogen incorporation into silicon. However, the range of this enhancement is limited to ∼1 nm, requiring additional trimethylaluminum exposures to continue the Si3N4 deposition.
L.MARIN MERCADO, A.ESTEVE, Y.GAO, Y.J.CHABAL, C.ROSSI
NEO, University of Texas
Manifestation avec acte : E-MRS Spring Meeting 2017 du 22 mai au 26 mai 2017, Strasbourg (France), Mai 2017, 1p. , N° 17086
A.NICOLLET, L.MARIN MERCADO, A.BELISARIO, C.ROSSI
Manifestation avec acte : E-MRS Spring Meeting 2017 du 22 mai au 26 mai 2017, Strasbourg (France), Mai 2017, 1p. , N° 17088
V.BAIJOT, M.DJAFARI ROUHANI, C.ROSSI, A.ESTEVE
Affiche/Poster : E-MRS Spring Meeting 2017 du 22 mai au 26 mai 2017, Strasbourg (France), Mai 2017, 1p. , N° 17087
T.CALAIS, V.BAIJOT, MC.BLATCHE, M.DJAFARI ROUHANI, Y.J.CHABAL, A.ESTEVE, C.ROSSI
NEO, I2C, University of Texas
Manifestation avec acte : E-MRS Spring Meeting 2017 du 22 mai au 26 mai 2017, Strasbourg (France), Mai 2017, 1p. , N° 17116
A.LAHIMER, A.ESTEVE, C.ROSSI
INSAT Tunis, NEO
Rapport de Contrat : Collaboration de recherche CNRS-LAAS/CEA-DAM n° 148672, Avril 2017, 25p. , N° 17096
Rédacteur invité : Propellants, Explosive, Pyrotechnics, Mars 2017, Vol.42, pp.235-236 , N° 17084