Élaboration de nanoparticules par décharges spark nanosecondes dans des liquides diélectriques : compréhension des mécanismes élémentaires et synthèse de composites

Abstract : Discharges in liquids offer a simple way to synthesize nanoparticles at high rate and low cost. When spark discharges are ignited in a dielectric liquid, a strong heating of the electrode material occurs, producing a metallic vapor from which nanoparticles grow by condensation. Even if most of the energy is dissipated in the formation of the discharge, the erosion of the metal electrodes allows the efficient production of NPs. The nature of the NPs formed is largely dependent on the dielectric liquid in which the discharge is performed. It is thus possible to control the nanoparticles produced by choosing the electrodes and the liquid in an appropriate manner. We seek in this work to understand the mechanisms that take place during the discharge by studying different cases of elaboration of NPs either alloys or composites. The synthesized NPs will have applications in various fields depending on the material(s) chosen. Using a nanosecond pulse generator, the discharges were created by applying a high voltage pulse (10 kV-200ns-10 Hz) between two electrodes immersed in liquid nitrogen. Three main systems have been studied: Si-Sn, Cu-Zn and Cu-Ag. The tests were performed with pure electrodes or alloys containing the 2 elements in varying proportions to improve our understanding of how nanoparticles are formed. High resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), electron energy loss spectroscopy (EELS) and micro-diffraction analyzes were carried out to characterize the synthesized NPs (morphology, crystallinity, chemical composition, etc.). Finally, time-resolved optical emission spectroscopy measurements were performed to obtain information on the temporal evolution of the lines emitted during the discharge and thus on the conditions that prevail in the plasma
Complete list of metadatas

Cited literature [277 references]  Display  Hide  Download

https://hal.univ-lorraine.fr/tel-01920241
Contributor : Thèses Ul <>
Submitted on : Monday, February 25, 2019 - 2:45:16 PM
Last modification on : Monday, February 25, 2019 - 2:50:15 PM
Long-term archiving on : Sunday, May 26, 2019 - 2:31:17 PM

File

DDOC_T_2018_0038_KABBARA.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01920241, version 1

Citation

Hiba Kabbara. Élaboration de nanoparticules par décharges spark nanosecondes dans des liquides diélectriques : compréhension des mécanismes élémentaires et synthèse de composites. Physique [physics]. Université de Lorraine, 2018. Français. ⟨NNT : 2018LORR0038⟩. ⟨tel-01920241⟩

Share

Metrics

Record views

61

Files downloads

118