High-energy electric discharge technologies (electric breakdown and HF volume discharge in organic 
media) for a large scale synthesis of amorphous carbon (AC) are developed. A destruction of hydrocarbon 
molecules into separate fragments occurs during such processing of organic media, what results in AC 
formation in the process of ultra-fast cooling of the clusters. To investigate the influence of chemical nature 
of working media, organic liquids and gases from the class of arenes with sp2-hybridisation of carbon atoms 
in molecule and alkanes with sp3-hybridisation were used. Performed XRD, HRTEM and Raman studies 
showed that produced powders are typical amorphous materials with significant degree of disorder. But 
only in the case of electric breakdown of alkanes, carbon nanomaterials with complex core-shell structure 
were discovered. Individual particles of onion-like carbon (OLC) consist of ~ 5 nm core surrounded by 
graphitic shell of 5-6 layers. Synthesized OLC is used as antifriction additives to industrial oils and as material for electromagnetic waves shielding. The statistical analysis of the atomic structure of the 
synthesized materials using reverse Monte Carlo and Voronoi-Delaunay methods was performed.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3509

Boguslavskii, L.Z.

Kiryan, I.M.

Kuskova, N.I.

Nazarova, N.S.

Petrichenko, S.V.

Rodionova, V.N.

Rud, A.D.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 1, 01NDLCN10(4pp) (2012)   2304-1862/2012/1(1)01NDLCN10(4) 01NDLCN10-1  2012 Sumy State University Electric Discharge Plasmochemical Synthesis of Carbon Nanomaterials  A.D. Rud1, N.I. Kuskova2, L.Z. Boguslavskii2, I.M. Kiryan1, S.V. Petrichenko2, N.S. Nazarova2, V.N. Rodionova3  1 G.V. Kurdyumov Institute for Metal Physics of NASU, 36 Vernadsky blvd., 03142 Kiev, Ukraine 2 Institute of Pulse Research and Engineering of NASU, 43a Oktyabrskii pr., 54018 Nikolaev, Ukraine 3 Institute of Nuclear Problems BSU, 11 Bobruiskaya str., 220050 Minsk, Belarus  (Received 26 July; published online 10 August 2012)  High-energy electric discharge technologies (electric breakdown and HF volume discharge in organic media) for a large scale synthesis of amorphous carbon (AC) are developed. A destruction of hydrocarbon molecules into separate fragments occurs during such processing of organic media, what results in AC formation in the process of ultra-fast cooling of the clusters. To investigate the influence of chemical nature of working media, organic liquids and gases from the class of arenes with sp2-hybridisation of carbon atoms in molecule and alkanes with sp3-hybridisation were used. Performed XRD, HRTEM and Raman studies showed that produced powders are typical amorphous materials with significant degree of disorder. But only in the case of electric breakdown of alkanes, carbon nanomaterials with complex core-shell structure were discovered. Individual particles of onion-like carbon (OLC) consist of ~ 5 nm core surrounded by graphitic shell of 5-6 layers. Synthesized OLC is used as antifriction additives to industrial oils and as ma-terial for electromagnetic waves shielding. The statistical analysis of the atomic structure of the synthesized materials using reverse Monte Carlo and Voronoi-Delaunay methods was performed.  Keywords: Carbon nanomaterials, Electric discharge synthesis, Onion-like carbon, Structure, Voronoi polihedra.    PACS numbers: 52.80. – s, 52.50. – b, 81.05.U – , 81.07. – b   1. INTRODUCTION  Despite the occurrence of the wide variety of methods for the synthesis of carbon nanomateriyals (CNM), a development of technologies for production of different allotropic forms of nanocarbon in large scale, necessary for industrial application, is still actual task. Therefore, high-voltage electrical discharge technologies of CNM synthesis (fullerenes, carbon nanotubes, nanodiamonds, onion-like carbon, amorphous carbon, etc.), based on the use of the methods of electric explosion of graphite rods (exploding wires), electrical breakdown of dielectric hy-drocarbons in the liquid and gaseous states and high-frequency (HF) plasma-discharge in gaseous hydrocar-bons are of great interest [1-5]. It was experimentally shown that the method of elec-tric explosion of graphite conductors enables to produce a wide spectrum of CNM [1,2]. Their phase composition can be effectively controlled by the amount of specific energy injected into graphite. The phase trajectories of graphite in the process of electric explosion are well de-scribed by a system of magnetohydrodynamic and elec-trodynamic equations [6, 7]. However, regardless of low prices and technological simplicity, the method of elec-tric explosion of graphite does not allow obtain CNM in the scales required for industrial application. In the Institute of Pulse Research and Engineering and G.V. Kurdyumov Institute for Metal Physics of NAS of Ukraine the high-voltage electric-discharge plasma-chemical methods of synthesis of large scale CNM were designed. In this paper the structural state of the CNM produced by the method of electrical breakdown of hydrocarbons and the method of volume high-frequency discharge in organic gases are studied.    2. ELECTRIC-DISCHARGE TECHNOLOGIES FOR CNM SYNTHESYS  The physical basis of electric-discharge methods for synthesis of various allotropic forms of CNM consists in nonequilibrium plasma formation from initial hydro-carbon medium, in which plasmo-chemical reactions of organic molecules destruction according to the scheme CnHk  =  nCs + 0.5kH2 with subsequent nanocarbon formation in process of ultra-fast clusters cooling take place.  The plasma is generated as result of high-voltage elec-trical breakdown of dielectric organic medium with help of generator of powerful current pulses (up to 1 MA, 0.1-10 Hz) or as result of initiation of volume high-frequency (5-50 kHz) gas discharge. The phase compo-sition and structure state of the produced CNM can be effectively controlled by the next:  through varying an energy injected into work-ing medium by changing the stored energy of a capacitor bank  and amount of current pulses;  through selecting an appropriate working me-dium – the source of carbon, i.e. use of hydro-carbons of different chemical nature. The method of electrical breakdown has been im-plemented in a chamber with a coaxial system of elec-trodes filled with the working medium - liquid or gase-ous hydrocarbons, which are differ in the degree of hy-bridization of carbon atoms and the structure of the molecule:  benzene (C6H6) - belongs to a class of arenes with sp2-hybridization of the carbon atoms in a planar ring molecule,  cyclohexane (C6H12) - belongs to a class of cycloal-kanes with sp3-hybridization of carbon atoms in a nonplanar ring molecule,  A.D. RUD, N.I. KUSKOVA, L.Z. BOGUSLAVSKII, ET AL. PROC. NAP 1, 01NDLCN10 (2012)   01NDLCN10-2  acetylene (C2H2) - belongs to a class of alkynes, with sp-hybridization of the atoms,  mixture of propane and butane (C3H8 + C4H10) - belongs to the class of alkanes, with sp3-hybridization of the carbon atoms. After series of electrical discharges (up to 20,000 pulses), working liquid containing colloidal solution of carbon nanoparticles was decanted from the discharge chamber and centrifuged during 0.3-2 hours. The pro-duced material is exsiccated at the sparing tempera-tures (up to 500 K) with a purpose to form dry powder. The experimental equipment for the synthesis of CNM by HF method consists of: - reactor, in which the mobile and stationary electrodes with the channels for the supply of gaseous feedstock and removal of reaction products are installed; - high-voltage HF pulse generator with adjustable out-put voltage from 3 to 30 kV and pulse repetition rate from 1 to 100 kHz. HF electric discharge synthesis was conducted in an environment of propane-butane and acetylene for various configurations of electrode systems at ambient and slightly elevated pressure and temperature in the reactor. Investigation of the nanocarbon microstructure was performed using high resolution electron microscope JEOL JEM-2100F. X-ray diffraction studies were car-ried out on a standard diffractometer with monochro-mated Mo K  radiation in the washing beam geometry.  3. STRUCTURE STATE OF THE SYNTHESIZED CARBON NANOMATERIALS   3.1 Exeperimental results   As result of the performed experiments, carbon pow-ders with low bulk density (~ 10 kg/m3) and developed surface (SBET ~ 50-300 m2/g) were synthesized on the electric discharge equipment in the above mentioned hydrocarbon media using the methods of electrical breakdown and HF electric discharge. High-resolution electron microscopy showed that produced carbon nano-materials possess an onion-like structure (Fig. 1a) in the case of use of hydrocarbons with sp3-hibridization (cyclo-hexane, propane-butane) as the working medium. It can be clearly seen that the particles are collected in agglom-erates (Fig. 1b). The individual particles have a spheroi-dal shape and size of ~ 5-10 nm. Deviation of graphene layers in a particle from the ideal spherical shape, in-herent in the onion-like structures, can be explained by incompleteness of the synthesis process. In the case of use of acetylene, amorphous carbon with disordered structure has been formed (Fig. 1c). Raman spectroscopy investigation has validated that the products of electric discharge treatment of various hydrocarbons are typical amorphous carbon material. The representative Raman spectra of the amor-phous carbon are characterized by intensive broad G- and D- bands (Fig. 1). The standard positions of D (1350 cm-1)- and G (1580 cm-1) -bands for graphite are indicated in the figures. The structural parameters calculated from the ratio of intensities of D-and G-bands have proved a strong structural disorder of the carbon powders: the value of La does not exceed 8 nm what correlates with that obtained from the high-resolution electron microscopy and structural data.    Fig. 1 – High-resolution micrographs of products of electric discharge treatment of propane-butane mixture (a), acetylene (b)  0501001000 1200 1400 1600 1800 2000050100150С6Н6GС6Н12D Raman Shift, cm-1Raman intensity   Fig. 2 – Typical Raman spectra of amorphous carbon obtained by electrical discharge treatment of benzene (a) and cyclohexane (b)  To determine the type of short-range order the method of radial distribution of atoms was used. Struc-ture factor (SF) and radial distribution function were calculated from the experimental diffraction data for all synthesized materials (Fig. 3).  It is clearly seen that SF of all powders is characterized by intense line S1 = 1.8 Å-1, whose position is typical for graphite.  Thus, the powders, synthesized at electrical dis-charge treatment of gaseous and liquid hydrocarbons, are amorphous carbon with a graphite type of short-range order. It is also well confirmed by the analysis of the radial distribution function of atoms.  Synthesized carbon nanomaterials were utilized as antifriction additives to industrial oils and as material for effective electromagnetic waves shielding. The re-flection factor and absorption factor measurements of the CNM samples were made in the frequency range from 25 to 37 GHz. The absorption coefficient of the OLC sample is in the band of 28-34 dB. 3.2 Statistical analysis of structure state of the CNM  Structural models of atomic configurations of car-bon nanomaterials produced from gaseous hydrocar-bons have been reconstructed employing experimental curves of the structure factor by means of the reverse Monte Carlo method [8]. Agreement of experimental  ELECTRIC DISCHARGE PLASMOCHEMICAL SYNTHESIS … PROC. NAP 1, 01NDLCN10 (2012)   01NDLCN10-3 and calculated structure factors (Fig. 3 c, d) indicates that the resulting model of the atomic positions corre-sponds to the realistic structure of the studied objects. For the models of generated atomic configurations of the synthesized amorphous carbon, bond angle distri-butions have been calculated (Fig. 4).   1 2 3 4 5 6 7 8 9 10 11 120246 d)     s, A-1  0246 c)  0246 b)s1 i(s)0246  0а)Fig. 3 – The structure factor of CNM produced by electric discharge treatment of liquid and gaseous hydrocarbons  (a - benzene; b - cyclohexane; c - mixture of propane and butane,  d - acetylene)  ── experiment ── modeling   Bond angle distributions are characterized by a broad intense peak at 60°, which is absent in the ones calculated for graphite and UDA (Fig. 4). From a crys-tal-chemistry point of view, this fact can be interpreted as an insertion of additional atoms into the centre of some hexamerous fragments of curved graphene layers of amorphous carbon. A less intensive maximum which occupies an intermediate position between the ones of graphite and UDA is also presents on the bond angle distributions for the synthesized materials (Fig. 4 a, b). To analyze the local atomic structure the model en-semble of atoms was divided into Voronoi polyhedra (VP) and Delaunay simplexes. The most widely appli-cable forms of the statistical geometrical analysis of random systems by VP are topological (distribution of the number of faces and the number of edges per face and topological types) properties and metric (distribu-tion of VP volumes, distribution of VP face areas, the radial distribution of geometrical neighbors, the sphe-ricity coefficient, etc.) ones [9]. Statistical analysis of Voronoi polyhedra, construct-ed for the models of atomic configurations of amor-phous carbon, generated by RMC method, showed that the VP with faces number of 15 dominate in the syn-thesized materials. It is also established that the Voro-noi polyhedra are mainly characterized by pentagonal faces, which do not correspond to crystal structures 20 40 60 80 100 120 140 160 18002      02b)  a)024     P( 0246  GraphiteUDA Fig. 4 – Bond angle distribution, calculated for models of atomic configurations generated by the RMC method: a – mixture of propane and butane, b – acetylene  and provide an amorphous state. The volume distribu-tions of VP of different carbon materials, calculated by presented in [10] algorithm, are shown in Fig. 5. It is clearly seen, that the curves for the produced nanocar-bon, as opposed to crystalline graphite and UDD, are characterized by an asymmetry and prolating toward higher volume values. Such kind of the volume distri-bution of VP indicates to a fact that the system is het-erogeneous, namely, the presence of large pores in atomic structure of AC.  0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4050010001500200025003000 C3H8+C4H10  C2H2 UDA Graphite  P(V)Volume, A30 Fig. 5 – Volume distribution of Voronoi polyhedra for synthesized carbon nanomaterials  4. CONCLUSIONS  High-energy electric discharge technologies (electric breakdown and HF volume discharge in organic media) for a large scale synthesis of amorphous carbon are developed. The synthesized materials possess almost homogeneous morphology: up to 90% of individual par-ticles have a similar shape with size of 10-20 nm. AC,  A.D. RUD, N.I. KUSKOVA, L.Z. BOGUSLAVSKII, ET AL. PROC. NAP 1, 01NDLCN10 (2012)   01NDLCN10-4 produced by HF plasma-discharge in gaseous hydro-carbons technique, practically consists of pure carbon. It eliminates the need of its separation and purifica-tion, what results in essential decrease of prime cost of the CNM. The structure of amorphous carbon produced by the technique of electric discharge treatment of organic media directly depends from chemical nature of the working medium – source of carbon. The fact of onion-like carbon synthesis by electric discharge treatment of hydrocarbons with sp3-hybridization (cyclohexane and propane-butane mixture) is established. Onion-like carbon was utilized as antifriction addi-tives to industrial oils and as material for effective electromagnetic waves shielding.     AKNOWLEDGEMENTS  This work was partially supported by the joint pro-ject of SFBR of Ukraine (#F41/220-2012) – RFBR of Belarus (T11K-130).     REFERENCES  1. A.D. Rud, N.I. Kuskova, L.I. Ivaschuk, L.Z. Boguslavskii and A.E. Perekos. Synthesis of Carbon Nanomaterials Us-ing High-Voltage Electric Discharge Techniques, Nano-materials, Mohammed Muzibur Rahman (Ed.) (2011), ISBN: 978-953-307-913-4, InTech, Available from: http://www.intechopen.com/articles/show/title/synthesis-of-carbon-nanomaterials-using-high-voltage-electric-discharge-techniques. 2. A.D. Rud, N.I. Kuskova, V.Yu. Baklar’, L.I. Ivaschuk, L.Z. Boguslavskii, I.M. Kiryan, Izvestiya Rossiiskoi Akademii Nauk. Seriya Fizicheskaya 75 No 11, 1526 (2011). 3. N.S. Koprinarov, M.A. Konstantinova, Fullerenes, Nano-tubes, and Carbon Nanostructures 20, 463 ( 2012). 4. S.A. Jdanok, A.V. Krauklis, I.F. Buyakov, V.M. Volzhankin, K.O. Borisevich, P.P. Samtsov, Inzhenerno-Fizicheskii Zhurnal 81 No 4, 143 (2008). 5. A.D. Rud, I. М. Kiryan, L.Z. Boguslavskii, G.M Zelinskaya, N.S.  Nazarova, D.V. Vinnichenko, Metallofiz. Noveishie Tekhnol. 33, 111 (2011). 6. N.I. Kuskova, Tech. Phys. Lett. 31 No7, 732 (2005). 7. V.I. Oreshkin, S.F. Chaikovsky, N.A. Labetskaya, Y.F. Ivanov, K.V. Hishchenko, P.R. Levashov, N.I. Kuskova, A.D. Rud, Zhurnal Tekhnicheskoi Fiziki 82, 2 (2012). 8. Metropolis N., Rosenbluth A.W. et al. J. Chem. Phys. 21, No6, 1087 (1953).  9. N.N. Medvedev, Voronoi-Delaunay method to study the structure of noncrystalline systems (RAS, Sibirsk. Depat-men, RFBR, Institute of Chemistry Kinetics and Combus-tion SD RAS: 2000). 10. N.N. Medvedev, V.P. Voloshin, V.A. Luchnikov, M.L. Gav-rilova, Comput. Chem. 27 (14), 1676 (2006).  

Electric Discharge Plasmochemical Synthesis of Carbon Nanomaterials

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 1, 01NDLCN10(4pp) (2012) 
 
 
2304-1862/2012/1(1)01NDLCN10(4) 01NDLCN10-1  2012 Sumy State University 
Electric Discharge Plasmochemical Synthesis of Carbon Nanomaterials 
 
A.D. Rud1, N.I. Kuskova2, L.Z. Boguslavskii2, I.M. Kiryan1, S.V. Petrichenko2, 
N.S. Nazarova2, V.N. Rodionova3 
 
1 G.V. Kurdyumov Institute for Metal Physics of NASU, 36 Vernadsky blvd., 03142 Kiev, Ukraine 
2 Institute of Pulse Research and Engineering of NASU, 43a Oktyabrskii pr., 54018 Nikolaev, Ukraine 
3 Institute of Nuclear Problems BSU, 11 Bobruiskaya str., 220050 Minsk, Belarus 
 
(Received 26 July; published online 10 August 2012) 
 
High-energy electric discharge technologies (electric breakdown and HF volume discharge in organic 
media) for a large scale synthesis of amorphous carbon (AC) are developed. A destruction of hydrocarbon 
molecules into separate fragments occurs during such processing of organic media, what results in AC 
formation in the process of ultra-fast cooling of the clusters. To investigate the influence of chemical nature 
of working media, organic liquids and gases from the class of arenes with sp2-hybridisation of carbon atoms 
in molecule and alkanes with sp3-hybridisation were used. Performed XRD, HRTEM and Raman studies 
showed that produced powders are typical amorphous materials with significant degree of disorder. But 
only in the case of electric breakdown of alkanes, carbon nanomaterials with complex core-shell structure 
were discovered. Individual particles of onion-like carbon (OLC) consist of ~ 5 nm core surrounded by 
graphitic shell of 5-6 layers. Synthesized OLC is used as antifriction additives to industrial oils and as ma-
terial for electromagnetic waves shielding. The statistical analysis of the atomic structure of the 
synthesized materials using reverse Monte Carlo and Voronoi-Delaunay methods was performed. 
 
Keywords: Carbon nanomaterials, Electric discharge synthesis, Onion-like carbon, Structure, Voronoi 
polihedra.  
 
 PACS numbers: 52.80. – s, 52.50. – b, 81.05.U – , 81.07. – b 
 
 
1. INTRODUCTION 
 
Despite the occurrence of the wide variety of methods 
for the synthesis of carbon nanomateriyals (CNM), a 
development of technologies for production of different 
allotropic forms of nanocarbon in large scale, necessary 
for industrial application, is still actual task. Therefore, 
high-voltage electrical discharge technologies of CNM 
synthesis (fullerenes, carbon nanotubes, nanodiamonds, 
onion-like carbon, amorphous carbon, etc.), based on the 
use of the methods of electric explosion of graphite rods 
(exploding wires), electrical breakdown of dielectric hy-
drocarbons in the liquid and gaseous states and high-
frequency (HF) plasma-discharge in gaseous hydrocar-
bons are of great interest [1-5]. 
It was experimentally shown that the method of elec-
tric explosion of graphite conductors enables to produce 
a wide spectrum of CNM [1,2]. Their phase composition 
can be effectively controlled by the amount of specific 
energy injected into graphite. The phase trajectories of 
graphite in the process of electric explosion are well de-
scribed by a system of magnetohydrodynamic and elec-
trodynamic equations [6, 7]. However, regardless of low 
prices and technological simplicity, the method of elec-
tric explosion of graphite does not allow obtain CNM in 
the scales required for industrial application. 
In the Institute of Pulse Research and Engineering 
and G.V. Kurdyumov Institute for Metal Physics of 
NAS of Ukraine the high-voltage electric-discharge 
plasma-chemical methods of synthesis of large scale 
CNM were designed. In this paper the structural state 
of the CNM produced by the method of electrical 
breakdown of hydrocarbons and the method of volume 
high-frequency discharge in organic gases are studied.  
 
 
2. ELECTRIC-DISCHARGE TECHNOLOGIES 
FOR CNM SYNTHESYS 
 
The physical basis of electric-discharge methods for 
synthesis of various allotropic forms of CNM consists in 
nonequilibrium plasma formation from initial hydro-
carbon medium, in which plasmo-chemical reactions of 
organic molecules destruction according to the scheme 
CnHk  =  nCs + 0.5kH2 
with subsequent nanocarbon formation in process of 
ultra-fast clusters cooling take place.  
The plasma is generated as result of high-voltage elec-
trical breakdown of dielectric organic medium with 
help of generator of powerful current pulses (up to 1 
MA, 0.1-10 Hz) or as result of initiation of volume high-
frequency (5-50 kHz) gas discharge. The phase compo-
sition and structure state of the produced CNM can be 
effectively controlled by the next: 
 through varying an energy injected into work-
ing medium by changing the stored energy of a 
capacitor bank  and amount of current pulses; 
 through selecting an appropriate working me-
dium – the source of carbon, i.e. use of hydro-
carbons of different chemical nature. 
The method of electrical breakdown has been im-
plemented in a chamber with a coaxial system of elec-
trodes filled with the working medium - liquid or gase-
ous hydrocarbons, which are differ in the degree of hy-
bridization of carbon atoms and the structure of the 
molecule: 
 benzene (C6H6) - belongs to a class of arenes with 
sp2-hybridization of the carbon atoms in a planar 
ring molecule, 
 cyclohexane (C6H12) - belongs to a class of cycloal-
kanes with sp3-hybridization of carbon atoms in a 
nonplanar ring molecule, 
 A.D. RUD, N.I. KUSKOVA, L.Z. BOGUSLAVSKII, ET AL. PROC. NAP 1, 01NDLCN10 (2012) 
 
 
01NDLCN10-2 
 acetylene (C2H2) - belongs to a class of alkynes, 
with sp-hybridization of the atoms, 
 mixture of propane and butane (C3H8 + C4H10) - 
belongs to the class of alkanes, with sp3-
hybridization of the carbon atoms. 
After series of electrical discharges (up to 20,000 
pulses), working liquid containing colloidal solution of 
carbon nanoparticles was decanted from the discharge 
chamber and centrifuged during 0.3-2 hours. The pro-
duced material is exsiccated at the sparing tempera-
tures (up to 500 K) with a purpose to form dry powder. 
The experimental equipment for the synthesis of 
CNM by HF method consists of: 
- reactor, in which the mobile and stationary electrodes 
with the channels for the supply of gaseous feedstock 
and removal of reaction products are installed; 
- high-voltage HF pulse generator with adjustable out-
put voltage from 3 to 30 kV and pulse repetition rate 
from 1 to 100 kHz. 
HF electric discharge synthesis was conducted in an 
environment of propane-butane and acetylene for various 
configurations of electrode systems at ambient and 
slightly elevated pressure and temperature in the reactor. 
Investigation of the nanocarbon microstructure was 
performed using high resolution electron microscope 
JEOL JEM-2100F. X-ray diffraction studies were car-
ried out on a standard diffractometer with monochro-
mated Mo K  radiation in the washing beam geometry. 
 
3. STRUCTURE STATE OF THE SYNTHESIZED 
CARBON NANOMATERIALS  
 
3.1 Exeperimental results  
 
As result of the performed experiments, carbon pow-
ders with low bulk density (~ 10 kg/m3) and developed 
surface (SBET ~ 50-300 m2/g) were synthesized on the 
electric discharge equipment in the above mentioned 
hydrocarbon media using the methods of electrical 
breakdown and HF electric discharge. High-resolution 
electron microscopy showed that produced carbon nano-
materials possess an onion-like structure (Fig. 1a) in the 
case of use of hydrocarbons with sp3-hibridization (cyclo-
hexane, propane-butane) as the working medium. It can 
be clearly seen that the particles are collected in agglom-
erates (Fig. 1b). The individual particles have a spheroi-
dal shape and size of ~ 5-10 nm. Deviation of graphene 
layers in a particle from the ideal spherical shape, in-
herent in the onion-like structures, can be explained by 
incompleteness of the synthesis process. In the case of 
use of acetylene, amorphous carbon with disordered 
structure has been formed (Fig. 1c). 
Raman spectroscopy investigation has validated that 
the products of electric discharge treatment of various 
hydrocarbons are typical amorphous carbon material. 
The representative Raman spectra of the amor-
phous carbon are characterized by intensive broad G- 
and D- bands (Fig. 1). The standard positions of D 
(1350 cm-1)- and G (1580 cm-1) -bands for graphite are 
indicated in the figures. The structural parameters 
calculated from the ratio of intensities of D-and G-
bands have proved a strong structural disorder of the 
carbon powders: the value of La does not exceed 8 nm 
what correlates with that obtained from the high-
resolution electron microscopy and structural data. 
  
 
Fig. 1 – High-resolution micrographs of products of electric 
discharge treatment of propane-butane mixture (a), acetylene (b) 
 
0
50
100
1000 1200 1400 1600 1800 2000
0
50
100
150
С
6
Н
6
G
С
6
Н
12
D
 Raman Shift, cm-1
R
a
m
a
n
 i
n
te
n
s
it
y
  
 
Fig. 2 – Typical Raman spectra of amorphous carbon obtained by 
electrical discharge treatment of benzene (a) and cyclohexane (b) 
 
To determine the type of short-range order the 
method of radial distribution of atoms was used. Struc-
ture factor (SF) and radial distribution function were 
calculated from the experimental diffraction data for 
all synthesized materials (Fig. 3).  It is clearly seen 
that SF of all powders is characterized by intense line 
S1 = 1.8 Å-1, whose position is typical for graphite.  
Thus, the powders, synthesized at electrical dis-
charge treatment of gaseous and liquid hydrocarbons, 
are amorphous carbon with a graphite type of short-
range order. It is also well confirmed by the analysis of 
the radial distribution function of atoms.  
Synthesized carbon nanomaterials were utilized as 
antifriction additives to industrial oils and as material 
for effective electromagnetic waves shielding. The re-
flection factor and absorption factor measurements of 
the CNM samples were made in the frequency range 
from 25 to 37 GHz. The absorption coefficient of the 
OLC sample is in the band of 28-34 dB. 
3.2 Statistical analysis of structure state of the 
CNM 
 
Structural models of atomic configurations of car-
bon nanomaterials produced from gaseous hydrocar-
bons have been reconstructed employing experimental 
curves of the structure factor by means of the reverse 
Monte Carlo method [8]. Agreement of experimental 
 ELECTRIC DISCHARGE PLASMOCHEMICAL SYNTHESIS … PROC. NAP 1, 01NDLCN10 (2012) 
 
 
01NDLCN10-3 
and calculated structure factors (Fig. 3 c, d) indicates 
that the resulting model of the atomic positions corre-
sponds to the realistic structure of the studied objects. 
For the models of generated atomic configurations of 
the synthesized amorphous carbon, bond angle distri-
butions have been calculated (Fig. 4).  
 
1 2 3 4 5 6 7 8 9 10 11 12
0
2
4
6 d)
     
s, A-1
 
 
0
2
4
6 c)
 
 
0
2
4
6 b)
s
1
 
i(s)
0
2
4
6
 
 
0
а)
Fig. 3 – The structure factor of CNM produced by electric 
discharge treatment of liquid and gaseous hydrocarbons  
(a - benzene; b - cyclohexane; c - mixture of propane and butane,  
d - acetylene)  
── experiment 
── modeling 
 
 Bond angle distributions are characterized by a 
broad intense peak at 60°, which is absent in the ones 
calculated for graphite and UDA (Fig. 4). From a crys-
tal-chemistry point of view, this fact can be interpreted 
as an insertion of additional atoms into the centre of 
some hexamerous fragments of curved graphene layers 
of amorphous carbon. A less intensive maximum which 
occupies an intermediate position between the ones of 
graphite and UDA is also presents on the bond angle 
distributions for the synthesized materials (Fig. 4 a, b). 
To analyze the local atomic structure the model en-
semble of atoms was divided into Voronoi polyhedra 
(VP) and Delaunay simplexes. The most widely appli-
cable forms of the statistical geometrical analysis of 
random systems by VP are topological (distribution of 
the number of faces and the number of edges per face 
and topological types) properties and metric (distribu-
tion of VP volumes, distribution of VP face areas, the 
radial distribution of geometrical neighbors, the sphe-
ricity coefficient, etc.) ones [9]. 
Statistical analysis of Voronoi polyhedra, construct-
ed for the models of atomic configurations of amor-
phous carbon, generated by RMC method, showed that 
the VP with faces number of 15 dominate in the syn-
thesized materials. It is also established that the Voro-
noi polyhedra are mainly characterized by pentagonal 
faces, which do not correspond to crystal structures 
20 40 60 80 100 120 140 160 180
0
2
     
 
0
2
b)
 
 
a)
0
2
4
     
P(
 
0
2
4
6
 
 Graphite
UDA
 
Fig. 4 – Bond angle distribution, calculated for models of 
atomic configurations generated by the RMC method: a – 
mixture of propane and butane, 
b – acetylene 
 
and provide an amorphous state. The volume distribu-
tions of VP of different carbon materials, calculated by 
presented in [10] algorithm, are shown in Fig. 5. It is 
clearly seen, that the curves for the produced nanocar-
bon, as opposed to crystalline graphite and UDD, are 
characterized by an asymmetry and prolating toward 
higher volume values. Such kind of the volume distri-
bution of VP indicates to a fact that the system is het-
erogeneous, namely, the presence of large pores in 
atomic structure of AC. 
 
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
0
500
1000
1500
2000
2500
3000
 C
3
H
8
+C
4
H
10
 
 C
2
H
2
 UDA
 Graphite
 
 
P
(V
)
Volume, A3
0
 
Fig. 5 – Volume distribution of Voronoi polyhedra for 
synthesized carbon nanomaterials 
 
4. CONCLUSIONS 
 
High-energy electric discharge technologies (electric 
breakdown and HF volume discharge in organic media) 
for a large scale synthesis of amorphous carbon are 
developed. The synthesized materials possess almost 
homogeneous morphology: up to 90% of individual par-
ticles have a similar shape with size of 10-20 nm. AC, 
 A.D. RUD, N.I. KUSKOVA, L.Z. BOGUSLAVSKII, ET AL. PROC. NAP 1, 01NDLCN10 (2012) 
 
 
01NDLCN10-4 
produced by HF plasma-discharge in gaseous hydro-
carbons technique, practically consists of pure carbon. 
It eliminates the need of its separation and purifica-
tion, what results in essential decrease of prime cost of 
the CNM. 
The structure of amorphous carbon produced by the 
technique of electric discharge treatment of organic 
media directly depends from chemical nature of the 
working medium – source of carbon. The fact of onion-
like carbon synthesis by electric discharge treatment of 
hydrocarbons with sp3-hybridization (cyclohexane and 
propane-butane mixture) is established. 
Onion-like carbon was utilized as antifriction addi-
tives to industrial oils and as material for effective 
electromagnetic waves shielding.    
 
AKNOWLEDGEMENTS 
 
This work was partially supported by the joint pro-
ject of SFBR of Ukraine (#F41/220-2012) – RFBR of 
Belarus (T11K-130).  
 
 
 
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Electric Discharge Plasmochemical Synthesis of Carbon Nanomaterials

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