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Your search keyword '"Djouadi, M.A."' showing total 49 results
Start Over Author "Djouadi, M.A." Publisher elsevier b.v.
49 results on '"Djouadi, M.A."'

47. Role of nitrogen doping at the surface of titanium nitride thin films towards capacitive charge storage enhancement.

Author

Achour, A., Chaker, M., Achour, H., Arman, A., Mardani, M., Islam, M., Boujtita, M., Le Brizoual, L., Djouadi, M.A., and Brousse, T.

Subjects
*DOPING agents (Chemistry), *ANNEALING of metals, *ELECTRODES, *THIN films, *TITANIUM nitride
Abstract

We recently reported an impressive cycling stability (over 20,000 cycles) of titanium nitride (TiN) electrodes with high specific capacitance. It is anticipated that nitrogen (β−N) doping in the oxidized surface of TiN film plays a crucial role in charge storage mechanism and stability of this material. In this work, we offer an evidence on the effect of β−N doping on improvement in specific capacitance of vacuum annealed TiN thin films. The annealing of the TiN films leads to the diffusion of the excess β−N from sub-surface to oxidized TiN film surface without further oxidation of the electrode surface. We demonstrate an increase in the TiN areal capacitance upon an increase in the amount of β−N dopant. The areal capacitance of the annealed films was enhanced by 3-fold (8.2 mF cm −2 in K 2 SO 4 aqueous electrolyte) without sacrificing the cycling stability of the electrodes after more than 10,000 consecutive charge/discharge cycles. [ABSTRACT FROM AUTHOR]

Published
2017
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48. Carbon nanotube growth mechanism switches from tip- to base-growth with decreasing catalyst particle size

Author

Gohier, A., Ewels, C.P., Minea, T.M., and Djouadi, M.A.

Subjects
*CARBON nanotubes, *CHEMICAL vapor deposition, *PARTICLES, *CATALYSTS, *COBALT, *NICKEL, *IRON
Abstract

Abstract: The growth of carbon nanotubes by a plasma assisted catalytic chemical vapor deposition was investigated using cobalt, nickel and iron catalyst particles of different sizes. For the three catalysts examined, it was shown that the growth mode switches from “tip-growth” for large particles (>>5nm) to “base-growth” for smaller ones (<5nm). While single-walled nanotubes and those with few walls (typically <7 walls) grow from their base, larger multi-walled nanotubes are fed with carbon via their tips which support the catalyst particle. A growth scenario involving two different pathways for carbon diffusion is proposed in order to explain the change in growth mode. [Copyright &y& Elsevier]

Published
2008
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49. Residual stress control in MoCr thin films deposited by ionized magnetron sputtering

Author

Tranchant, J., Angleraud, B., Tessier, P.Y., Besland, M.P., Landesman, J.P., and Djouadi, M.A.

Subjects
*THIN films, *RESIDUAL stresses, *SPUTTERING (Physics), *EMISSION spectroscopy
Abstract

Abstract: This study reports on the control of intrinsic stress in MoCr films deposited by ionized magnetron sputtering using a secondary plasma created through a radio-frequency (13.56 MHz) antenna. The efficiency of the additional antenna has been investigated by optical emission spectroscopy for a MoCr target. It appears that ionization of the sputtered species is significantly enhanced compared to a conventional magnetron sputtering. Moreover, by controlling the substrate bias, the RF power on the antenna and the discharge gas pressure (argon), the ion energy and flux can be strongly modified. Therefore, we have the ability to act on composition, growth rate, microstructure and residual stress of the deposited film. Indeed, the films exhibit residual stress varying from compressive value (−3.4 GPa) to tensile one (1.7 GPa). In particular, only by varying the RF power on the antenna, a wide range of tensile and compressive stress can be obtained without affecting the chemical composition of the films. These results will be useful when elaborating stress-engineered micro-objects such as micro-springs. [Copyright &y& Elsevier]

Published
2006
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