Nanomaterials synthesis at atmospheric pressure using nanosecond discharges

Abstract

The application of nanosecond discharges towards nanomaterials synthesis at atmospheric pressure is explored. First, various plasma sources are evaluated in terms of the energy used to include one atom into the nanomaterial, which is shown to depend strongly on the electron temperature. Because of their high average electron temperature, nanosecond discharges could be used to achieve nanofabrication at a lower energy cost, and therefore with better efficiency, than with other plasma sources at atmospheric pressure. Transient spark discharges and nanosecond repetitively pulsed (NRP) discharges are suggested as particularly useful examples of nanosecond discharges generated at high repetition frequency. Nanosecond discharges also generate fast heating and cooling rates that could be exploited to produce metastable nanomaterials.

Fast gas heating in N 2 /O 2 mixtures under nanosecond surface dielectric barrier discharge: the effects of gas pressure and composition

“…At such high values of E/N, a high percentage of the discharge energy is spent on ionization and one of the main mechanisms of fast gas heating is associated with electron-ion and ion-ion recombination. These conditions are met in high-voltage nanosecond discharges that are being increasingly used for aerodynamic flow control [8,9], plasma-assisted combustion [10][11][12], material processing [13] and for some other applications. That is why much attention has been given to experimental [6,[14][15][16][17][18] and computational [6,7,[19][20][21][22][23] studies of fast gas heating in nanosecond discharges and in their afterglows.…”

Energy efficiency in nanoscale synthesis using nanosecond plasmas

“…Non-thermal plasmas efficiently channel energy towards generating plasma chemical species such as electrons, ions, excited neutral species, and radicals typically not found in other synthesis environments that can serve as vehicles for the specific transfer of energy towards growth processes. So far, little attention has been paid to efficiency until recently1920.…”

“…This subject has been explored previously in a perspectives article19. NRP discharges are generated by applying high-voltage nanosecond-duration pulses at high pulse repetition frequency (PRF), as shown in Figure 2.…”

“…1 and 19 that plasmas and NRP discharges in particular can be potentially used for targeted and efficient use of energy and matter in nanoscale synthesis, here we employ NRP spark discharges for controlling the production of metal and oxygen atoms in open ambient air, resulting in the synthesis of high quality MO 3 nanostructures suitable for various applications. When metal electrodes for plasma generation also serve as the source for metal precursor atoms, it is convenient to use spark discharges because they generate temperatures high enough for evaporating metal222324.…”

Aerodynamic model of spark discharge

“…Nanomaterial synthesis at atmospheric pressure using nanosecond discharges is presented by Pai. [1] There is increasing interest in operating at atmospheric pressure where high species densities may permit fast synthesis without vacuum conditions. Pai [1] also presents a list of different applications of nanosecond discharges in the fabrication of nanomaterials.…”