Section “Nanocomposites and Nanomaterials”
Vacuum synthesis of carbon nanostructures from carbon-containing gas with the addition of a plasma component to it
Svavil’nyi M.Ye., Panarin V.Ye., Shkola A.A.

G.V. Kurdyumov Institute for Metal Physics of the National Academy of Sciences of Ukraine, blvd. Acad. Vernadsky 36, Kyiv-03142, Ukraine.
E-mail: myksvavil@gmail.com  

The report will present the results of experimental studies of the synthesis of carbon nanostructures with the addition of at least 1% of the plasma component of the gas to the working gas. Installation and measurement procedures are described in [1]. C2H2 and CH4 were used as the working gas. The working gas plasma was generated by a separate source in the form of a Penning discharge. High-temperature synthesis was carried out on Si, SiO2, and Ti foil substrates. Ni, Fe were used as catalysts. When the plasma component in the working gas entering the substrate did not exceed 0.01%, carbon nanotubes (CNTs), which we studied earlier [2], were synthesized on the catalytic centers of the substrates.
With an increase in the plasma component, reaching ~ 1% of the total particle flux, the appearance of the synthesized coating becomes similar to vertically oriented graphene "flakes" [3]. The resulting structure is practically the same for substrates of different physical nature, and also does not depend on whether there is a catalyst on the substrate or not.
To clarify the role of individual components of the working gas plasma in the synthesis of graphene-like structures, the substrate was covered with a nickel mesh with a cell size of ~ 180 μm. She was under "floating" potential. Under these conditions, neutral molecules of the working gas (including those excited to different quantum states) and the ionic component of the gas plasma could enter the substrate area inside the grid, but low-energy plasma electrons are unable to overcome the potential barrier formed in the ionic layer near the grid.
In conditions without such electrons, an amorphous carbon structure is synthesized inside the grid cell. Consequently, the formation of vertically oriented graphene "flakes" is played by low-energy electrons of the plasma flow.

1. Panarin V.Ye., Svavil’nyi N.Ye., Khominich A.I., Shkola A.A. On the analogy of physical and chemical processes of the directed grows of crystals and carbon nanotubes // Applied Nanoscience. -2020.-10. -Р. 2885-2895.
2. Panarin V.Ye., Svavil’nyi N.Ye., Khominich A.I.,An experimental study of the composite CNT/copper coating // Applied Nanosсiense.-2019.- 9. -P.1111–1117.
3. Svavil'nyi M.Ye., Panarin V.Ye., Shkola A.A., Nikolenko A.S., Strelchuk V.V. Plasma Enhanced Chemical Vapor Deposition synthesis of graphene-like structures
from plasma state of CO2 gas // Carbon. -2020.-167. -P. 132-139.