Interaction of atomized colloid with an ac electric field in a dielectric barrier discharge reactor used for deposition of nanocomposite coatings

Abstract

Nanocomposite thin films can be obtained by polymerization of a colloidal solution in a dielectric barrier discharge (DBD) at atmospheric pressure. In such a process, the dispersion of nanoparticles into the matrix is driven by the charging, transport, and deposition dynamics of the atomized colloid. This work examines the interaction of atomized TiO2 nanoparticles with ac electric fields in a plane-to-plane dielectric barrier discharge reactor. Experiments are performed with the discharge off to examine transport and deposition phenomena over a wide range of experimental conditions with a fixed particle charge distribution. Scanning electron microscopy reveals that the size distribution of TiO2 nanoparticles collected at different locations along the substrate surface placed on the bottom electrode of the DBD reactor can judiciously be controlled by varying the amplitude and frequency of the ac electric field. These results are also compared to the predictions of a simple particle motion model accounting for the electrostatic force, the gravitational force, and the neutral drag force in the laminar flow. It is found that while the initial charge distribution of atomized particles strongly influences the total deposition yield, its maximal position on the substrate, and the width of the deposited area, the initial size distribution of the particles at the entrance of the reactor mostly changes the size distribution at each position along the substrate surface.

Control of composite thin film made in an Ar/isopropanol/TiO2 nanoparticles dielectric barrier discharge by the excitation frequency

“…The transport of the NPs in a plasma is governed by different forces that include gravity, neutral, and ion drag, thermophoresis and electrostatic forces . The last three forces are related to the plasma characteristics.…”

“…This simplify model was actually inspired from ref . However, in our case, the NPs are bigger than in reference (>100 nm). Therefore, we believe that the simulations are of strong interest to take into account the aggregation of the NPs contained in the droplets after atomization .…”

“…Thus, the ion drag and thermophoresis forces are negligible as compared to the electrostatic and neutral drag forces . This simplify model was actually inspired from ref . However, in our case, the NPs are bigger than in reference (>100 nm).…”

“…However, for a sinusoidal voltage this remains true as far as the voltage frequency is low enough to allow a NP oscillation amplitude larger than the gas gap. As investigate by Profili et al, in the case of a Townsend discharge, an increase of the applied frequency produces the drastic decrease of the NPs concentration. Moreover it seems that in their configuration, most of the NPs are deposited before the edge of the DBD electrode due to the shape of the electric field in this area.…”

Atmospheric‐pressure plasma‐enhanced chemical vapor deposition of nanocomposite thin films from ethyl lactate and silica nanoparticles

“…An innovative approach based on atmospheric‐pressure plasma‐enhanced chemical vapor deposition (AP‐PECVD), [ 15 ] to create materials with desired properties and the controlled ratio of NPs within the plasma‐deposited film, has recently been considered. [ 3,8,16–20 ] Essentially, it is a two‐step process. The first step is the preparation of a suspension of NPs in a solvent.…”