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Plasma and powders

by Agnès GP - published on


The formation of nano composite thin films by plasma process involves two main mechanisms: deposition and matrix self organization and/or, secondly, powder formation in the plasma phase and deposition.

Active species formed in the discharge can react between themselves to initiate the powder growth process (homogeneous and heterogeneous reactions). In these processes, it is necessary to confine active seed species in the discharge (thank their negative ion confinement).

Our powder activities include three different axes:

  • Pulsed plasma in SiH4/N2O mixtures in which it is possible to adjust the silicon particle size from nanometer to micrometer with the process parameters.

Laser light scattering on Dusty plasma cloud in HMDSO/Ar in a RF diode reactor.
  • Magnetic confinement in Direct Electron Cyclotron Resonance microwave plasma in C2H2 which produces spherical “graphitic” powders of about 100-nm size.

powders formation in MMP-DECR located in strong magnetic field areas (lobes). View of few helical trajectories of powder leaving lobes and indicating the rotating effect induced by the magnetic field on the negative clusters during their growth)
  • Atmospheric Pressure Discharge in SiH4/N2O mixtures diluted in N2 in which changing the gas flow rates and / or creating gas re-circulation modulate the powder density and their production area.

Hydro-dynamic simulation carried out in FLUENT© showing recirculation areas identified as being powder trapping area in the case of deposition in DBD at atmospheric pressure.

- The growth on powders injected into the discharge by a physical process has been studied to form powder mixed structures (heart and shell of different structures): metal sputtering in RF plasma polymerization, metal evaporation in DECR microwave plasma, powder fluidized bed in reactive post-discharge. Thus, according to the methods used, different types of powders and therefore nano composite thin films are formed. The control of the network structure, chemical composition, powder size and the powder influence on the plasma physics and the plasma chemistry (species consumption and electrical discharge disturbance) are important scientific stakes on which scientific special effort will be conducted.

MicroSIMS of a C-C nano composite deposited in DECR microwave plasma. The powder (diameter = 400nm) is composed of a metallic core (Ni yellow) and a graphite shell. The matrix is an amorphous carbon (a-C H) (magenta) and C2H2 dimer (cyan). The diffuse interface (color mixing) between the shell and the core suggests that the powder is formed by catalytic growth mechanism (similar to the fullerene nanostructures (onion type).

References:

Thesis:

  • Maria Calafat Ramirez (2008), « Formation de poudres dans des décharges d’acétylène dans un réacteur PMM- RCER : Etudes des nanocomposites carbone-carbone et de leurs applications »

Main publications:

  • M. Calafat-Ramirez, D. Escaich, R. Clergereaux, P. Raynaud, Yvan Segui ; Particle formation in acetylene very low-pressure high density magnetized plasmas ; Applied Physics Letters, 2007, 181502 (3pages)
  • R. Clergereaux, D. Escaich, M. Calafat, P. Raynaud ; Dépôt, érosion et formation de poudres dans des plasmas haute densité, très faible pression d’hydrocarbonés. Plasmas froids à confinement magnétique pour la compréhension du plasma de bord ; Réunion plénière du GDR Arches, Nouan le Fuzelier, 2007
  • M. Calafat-Ramirez, P. Raynaud, R. Clergereaux ; Dusts in microwave distributed electron cyclotron resonance discharge in acetylene ; CIP 2007: 16th International Colloquium on Plasma Processes, Toulouse, France, 2007
  • M. Calafat, R. Clergereaux ; Formation de particules dans un plasma micro-onde basse pression haute densité à partir d’acétylène ; Journées scientifiques du groupe français du carbone, GFEC 2007, Caracans-Maubuisson
  • Clergereaux R., Escaich D., Calafat M., Raynaud P. ; Dépôt, erosion et formation de poudres dans des plasmas haute densité, très faible pression d’hydrocarbonés. Plasmas froids à confinement magnétique pour la compréhension du plasma de bord ; Réunion plénière, GDR ARCHES (2007)
  • M. Calafat-Ramirez, H. Kihel, R. Clergereaux ; Nanocomposites from very-low pressure dusty plasma ; 15th GEM: Gaseous Electronics Meeting, Murramarang , Australia, 2008
  • R. Clergereaux, F. Gaboriau, A. Slim, J. Stehlé, D. Zahorski, P. Raynaud ; Carbon-carbon nanocomposite formation in plasma deposition process ; JNTE 08: French Symposium on Emerging Technologies, Toulouse, France, 2008
  • R. Clergereaux, M. Calafat-Ramirez, A. Slim, A. Erradi, S. Mouissat, S. Sahli, F. Gaboriau ; Formation de poudres dans un plasma magnétisé, haute densité, basse pression ; 3ème Colloque sur la Cinétique des Plasmas : Recherches et Applications, Le Havre , France, 2008
  • R. Clergereaux, M. Calafat, P. Raynaud, F. Gaboriau ; Carbon-carbon nanocomposite thin films based on fullerene-like powder in hydrocarbon matrix formed in ECR plasma ; ISPC, Bochum (2009)

Contractual activities:
European project Napolyde, ANR Biopleasure

Internal collaborations:
PRHE

Scientific collaborations:
GDR Surgeco, GDR Arches, LGC, University of Barcelona (Spain)

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