According to SEM, X-ray phase analysis, Raman scattering data features of nanostructural changes in shungite carbon structure were found when processing shungite in 52 % hydrofluoric acid. It is found that conductivity increases up to the values of electrical graphite and absorption of microwave radiation also increases at frequencies up to 40 GHz, which, along with dielectric losses, is due to intense processes of both scattering at laminar carbon structures and absorption of electromagnetic energy.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3365

Dobromyslov, M.

Emelyanov, S.

Kuzmenko, A.

Rodionov, V.

SocioEconomic Challenges Journal (Sumy State University)

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ 
Vol. 5 No 4, 04023(3pp) (2013) Том 5 № 4, 04023(3cc) (2013) 
 
 
The article was reported at the International Conference «Physics and Technology of Nanomaterials and Structures», Kursk, 21-22 November, 2013 
2077-6772/2013/5(4)04023(3) 04023-1  2013 Sumy State University 
Short Communication 
 
Mechanisms of Microwave Absorption in Carbon Compounds from Shungite 
 
S. Emelyanov1, A. Kuzmenko1, V. Rodionov1, M. Dobromyslov2 
 
1 Southwest State University, 94, 50 Let Oktyabrya Str., 305040 Kursk, Russia 
2 Pacific National University, 136, Tihookeanskaya Str., 680035 Khabarovsk, Russia 
 
(Received 24 October 2013; published online 10 December 2013) 
 
According to SEM, X-ray phase analysis, Raman scattering data features of nanostructural changes in 
shungite carbon structure were found when processing shungite in 52 % hydrofluoric acid. It is found that 
conductivity increases up to the values of electrical graphite and absorption of microwave radiation also 
increases at frequencies up to 40 GHz, which, along with dielectric losses, is due to intense processes of 
both scattering at laminar carbon structures and absorption of electromagnetic energy. 
 
Keywords: Scanning electron microscopy, X-ray diffraction, Small-angle X-ray scattering, Raman 
scattering spectroscopy, Mapping of Raman shift distributions, Microwave absorption, Shungite. 
 
PACS numbers: 07.78. + s, 07.85.Fv, 42.65.Dr, 07.57. – c 
 
 
1. INTRODUCTION 
 
Micro- and nanostructural features of naturally-
doped minerals-shungites that have particles not 
greater than 100 nm in size and coherent scattering 
areas of several nanometers are of interest for studying 
the attenuation mechanisms in microwave range [1, 2]. 
So mechanically and chemically disintegrated 
shungites from Sazhogin deposits have been studied 
according to the procedure described in [3] with the 
chemical processing 6HF + SiO2 → H2[SiF6] + 2H2O. 
2. EXPERIMENTAL SECTION 
 
Element distribution in cleavages of chosen 
samples (JEOL JSM6610LV, EDX Oxford 
Instruments) was typical and is given in Fig. 1a-d 
with mapping data with a resolution of 1 m. After 
chemical processing the structure turned 
delaminated, and the particles became oval with an 
average diameter of up to 100 m (Fig 2a). The 
carbon content, according to increase by 6 %. The 
increase in content of metals occurs and the silicon 
content dropped off ten-fold. 
 
              
 
              
 
Fig. 1 – SEM-images of shungite (a) with a resolution of  1 m with elemental contrast: b – C, c- Si, d- O  
a b 
c d 
 S.EMELYANOV, A. KUZMENKO, V. RODIONOV, ET AL. J. NANO- ELECTRON. PHYS. 5, 04023 (2013) 
 
 
04023-2 
 
 
 
 
Fig. 2 – SEM of HF processed shungite powder (top). 
Eelemental composition (%) before (black) and after 
processing (grey) (bottom) 
 
 
 
Fig. 3 – X-ray patterns of shungite before and after processing 
 
Analysis of shungite phase composition (GBC 
ЕMMA, CuK) before and after processing is given in 
Fig. 3. It is found that it belongs to shungites of the 
1 type (reflection in the neighborhood of 2  80[2]). 
The reflections of all modifications of quartz and 
carbon structures typical of shungite were observed. 
Using diffraction patterns before and after processing 
the sizes of carbon nanostructures have been 
calculated (the coherent scattering areas (L) of X-ray 
radiation) from the Scherer equation: L  k/(Bcos). 
The reflection width was considered by the level 0.5 
(B), θ is the Bragg angle,   0.154178 nm for CuK, 
k is a constant equal to 0.9 for reflections to the plane 
(002) and 1.84 to the plane (10) according to [2]. For 
the plane (100) we adopted k  1.4. The predicted 
sizes of L are shown in Table 1 in comparison both 
with sizes in [2] and those according to small-angle 
X-ray scattering data (SAXSees mc2, CuK). 
Table 1 – Predicted sizes of carbon nanostructures 
 
Samples 
B, 
degree 
2, 
degree 
L100, nм 
Initial 4.5 26 3.6 
After HF 8.0 26 5.5 
According 
to [2] 
3.9 – 5.4 
SAXSess – – 5.1 
 
Raman scattering spectra on samples before and 
after processing shungite were examined with a 
resolution of 500 nm with a spectral resolution of up 
to 0.8 сm – 1 (OmegaScope, SmartSPM) and are 
shown in Fig.4. I this case excited were lines D – A1g 
(1354 сm – 1) – vibration of the whole carbon 
structure and G – E2g (1593 сm – 1) – antisymmetric 
vibration of carbon structures and the second order 
lines 2D – 2688 and 2G – 2916 сm – 1. The 
amorphization level K by the variation of ID – A1g и 
IG – E2g: K  (ID + IG)/(ID – IG) in shungite before and 
after processing was  5 и  8, respectively. The lines 
of fullerenes 450 and 190 сm – 1 with their content of 
up to 2 % were found in Raman spectra by mapping 
the cleavage surfaces of shungite (scans of 
900 spectra 60  60 m). 
Conductivity of shungite samples in the form of 
pressed tablets (220 аtm, 1  10  20 mm) examined 
with the LCR-meter Instek LCR-819 is characterized 
by an order of magnitude increase, up to the value for 
ordinary graphite. Nonlinear increase is observed to 
600 K and a succeeding saturation in the range 
measured to 800 K. All samples are characterized by 
high absorbing capacity (Fig. 5a, b) of microwave 
radiation (PNA-L Agilent N5230A, 12.6 – 40 GHz). 
 
 
 
Fig. 4 – Raman spectra of shungite before (  ) and 
after HF processing (  ). One of 900 scans of 
Raman scattering with lines С60 (  ) 
 
3. RESULTS AND DISCUSSION 
 
The transmission coefficient within the range 
19.6 and 21.7 GHz was equal on average to – 21 dB, 
and on 29.1 GHz – 39 dB. The shungite transmission 
coefficient S21 is probably due to multiple reflections 
and absorptions within laminar carbon structures 
(Fig. 2). This fact is also indicated by the observed 
decrease in S21 for the sample from – 9.5 dB to –
 44.5 dB at 13.6 GHz and 38.5 GHz, respectively,  
С
 –
 1
5
.3
 
С
6
0
 –
 4
0
.3
 
S
iO
2
  
- 
2
6
.6
 
С
 –
 2
5
.8
 
С
6
0
 –
 3
0
.8
 
 MECHANISMS OF MICROWAVE ABSORPTION IN CARBON COMPOUNDS… J. NANO- ELECTRON. PHYS. 5, 04023 (2013) 
 
 
04023-3 
 
 
 
 
Fig. 5 – Amplitude-frequency characteristic of S21 before 
(top) and after HF processing (bottom) of shungite 
 
that is more than 4.5-fold. The depth of skin layer for 
microwave radiation:   (f)-1/2 (f is frequency of 
electromagnetic radiation,   0 is suppressor 
penetrability, 0 is permeability of vacuum,  is 
electroconductivity) turns out to be much greater 
than the sizes of nanocarbon laminar structures, 
which adds to multiple reflections. Also, as shown in 
Fig. 5, the surface eddy currents grow. When 
RC  RMе, the Joule heat loss increases.  
 
4. CONCLUSIONS 
 
Thus, the increase of microwave radiation 
absorption in derivatives from shungite carbon 
structures, in addition to dielectric losses, is due to 
intense processes of both scattering and absorption of 
electromagnetic energy. 
 
 
 
REFERENCES 
 
1. F. Qin, C. Brosseau, J. App. Phys. 111, 061301 (2012). 
2. V.V. Kovalevski, P.R. Buseck, J.M. Cowley, Carbon 39, 
243 (2001). 
3. A.P. Kuzmenko, V.M. Emelianov, V.E. Dreizin, S.A. Efanov, 
V.V. Rodionov, Proceedings of the Southwest State 
University 2 (2012). 
 


English

Mechanisms of Microwave Absorption in Carbon Compounds from Shungite

Electronic Sumy State University Institutional Repository

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ Vol. 5 No 4, 04023(3pp) (2013) Том 5 № 4, 04023(3cc) (2013)   The article was reported at the International Conference «Physics and Technology of Nanomaterials and Structures», Kursk, 21-22 November, 2013 2077-6772/2013/5(4)04023(3) 04023-1  2013 Sumy State University Short Communication  Mechanisms of Microwave Absorption in Carbon Compounds from Shungite  S. Emelyanov1, A. Kuzmenko1, V. Rodionov1, M. Dobromyslov2  1 Southwest State University, 94, 50 Let Oktyabrya Str., 305040 Kursk, Russia 2 Pacific National University, 136, Tihookeanskaya Str., 680035 Khabarovsk, Russia  (Received 24 October 2013; published online 10 December 2013)  According to SEM, X-ray phase analysis, Raman scattering data features of nanostructural changes in shungite carbon structure were found when processing shungite in 52 % hydrofluoric acid. It is found that conductivity increases up to the values of electrical graphite and absorption of microwave radiation also increases at frequencies up to 40 GHz, which, along with dielectric losses, is due to intense processes of both scattering at laminar carbon structures and absorption of electromagnetic energy.  Keywords: Scanning electron microscopy, X-ray diffraction, Small-angle X-ray scattering, Raman scattering spectroscopy, Mapping of Raman shift distributions, Microwave absorption, Shungite.  PACS numbers: 07.78. + s, 07.85.Fv, 42.65.Dr, 07.57. – c   1. INTRODUCTION  Micro- and nanostructural features of naturally-doped minerals-shungites that have particles not greater than 100 nm in size and coherent scattering areas of several nanometers are of interest for studying the attenuation mechanisms in microwave range [1, 2]. So mechanically and chemically disintegrated shungites from Sazhogin deposits have been studied according to the procedure described in [3] with the chemical processing 6HF + SiO2 → H2[SiF6] + 2H2O. 2. EXPERIMENTAL SECTION  Element distribution in cleavages of chosen samples (JEOL JSM6610LV, EDX Oxford Instruments) was typical and is given in Fig. 1a-d with mapping data with a resolution of 1 m. After chemical processing the structure turned delaminated, and the particles became oval with an average diameter of up to 100 m (Fig 2a). The carbon content, according to increase by 6 %. The increase in content of metals occurs and the silicon content dropped off ten-fold.                                Fig. 1 – SEM-images of shungite (a) with a resolution of  1 m with elemental contrast: b – C, c- Si, d- O  a b c d  S.EMELYANOV, A. KUZMENKO, V. RODIONOV, ET AL. J. NANO- ELECTRON. PHYS. 5, 04023 (2013)   04023-2     Fig. 2 – SEM of HF processed shungite powder (top). Eelemental composition (%) before (black) and after processing (grey) (bottom)    Fig. 3 – X-ray patterns of shungite before and after processing  Analysis of shungite phase composition (GBC ЕMMA, CuK) before and after processing is given in Fig. 3. It is found that it belongs to shungites of the 1 type (reflection in the neighborhood of 2  80[2]). The reflections of all modifications of quartz and carbon structures typical of shungite were observed. Using diffraction patterns before and after processing the sizes of carbon nanostructures have been calculated (the coherent scattering areas (L) of X-ray radiation) from the Scherer equation: L  k/(Bcos). The reflection width was considered by the level 0.5 (B), θ is the Bragg angle,   0.154178 nm for CuK, k is a constant equal to 0.9 for reflections to the plane (002) and 1.84 to the plane (10) according to [2]. For the plane (100) we adopted k  1.4. The predicted sizes of L are shown in Table 1 in comparison both with sizes in [2] and those according to small-angle X-ray scattering data (SAXSees mc2, CuK). Table 1 – Predicted sizes of carbon nanostructures  Samples B, degree 2, degree L100, nм Initial 4.5 26 3.6 After HF 8.0 26 5.5 According to [2] 3.9 – 5.4 SAXSess – – 5.1  Raman scattering spectra on samples before and after processing shungite were examined with a resolution of 500 nm with a spectral resolution of up to 0.8 сm – 1 (OmegaScope, SmartSPM) and are shown in Fig.4. I this case excited were lines D – A1g (1354 сm – 1) – vibration of the whole carbon structure and G – E2g (1593 сm – 1) – antisymmetric vibration of carbon structures and the second order lines 2D – 2688 and 2G – 2916 сm – 1. The amorphization level K by the variation of ID – A1g и IG – E2g: K  (ID + IG)/(ID – IG) in shungite before and after processing was  5 и  8, respectively. The lines of fullerenes 450 and 190 сm – 1 with their content of up to 2 % were found in Raman spectra by mapping the cleavage surfaces of shungite (scans of 900 spectra 60  60 m). Conductivity of shungite samples in the form of pressed tablets (220 аtm, 1  10  20 mm) examined with the LCR-meter Instek LCR-819 is characterized by an order of magnitude increase, up to the value for ordinary graphite. Nonlinear increase is observed to 600 K and a succeeding saturation in the range measured to 800 K. All samples are characterized by high absorbing capacity (Fig. 5a, b) of microwave radiation (PNA-L Agilent N5230A, 12.6 – 40 GHz).    Fig. 4 – Raman spectra of shungite before (  ) and after HF processing (  ). One of 900 scans of Raman scattering with lines С60 (  )  3. RESULTS AND DISCUSSION  The transmission coefficient within the range 19.6 and 21.7 GHz was equal on average to – 21 dB, and on 29.1 GHz – 39 dB. The shungite transmission coefficient S21 is probably due to multiple reflections and absorptions within laminar carbon structures (Fig. 2). This fact is also indicated by the observed decrease in S21 for the sample from – 9.5 dB to – 44.5 dB at 13.6 GHz and 38.5 GHz, respectively,  С – 15.3 С60 – 40.3 SiO2  - 26.6 С – 25.8 С60 – 30.8  MECHANISMS OF MICROWAVE ABSORPTION IN CARBON COMPOUNDS… J. NANO- ELECTRON. PHYS. 5, 04023 (2013)   04023-3     Fig. 5 – Amplitude-frequency characteristic of S21 before (top) and after HF processing (bottom) of shungite  that is more than 4.5-fold. The depth of skin layer for microwave radiation:   (f)-1/2 (f is frequency of electromagnetic radiation,   0 is suppressor penetrability, 0 is permeability of vacuum,  is electroconductivity) turns out to be much greater than the sizes of nanocarbon laminar structures, which adds to multiple reflections. Also, as shown in Fig. 5, the surface eddy currents grow. When RC  RMе, the Joule heat loss increases.   4. CONCLUSIONS  Thus, the increase of microwave radiation absorption in derivatives from shungite carbon structures, in addition to dielectric losses, is due to intense processes of both scattering and absorption of electromagnetic energy.    REFERENCES  1. F. Qin, C. Brosseau, J. App. Phys. 111, 061301 (2012). 2. V.V. Kovalevski, P.R. Buseck, J.M. Cowley, Carbon 39, 243 (2001). 3. A.P. Kuzmenko, V.M. Emelianov, V.E. Dreizin, S.A. Efanov, V.V. Rodionov, Proceedings of the Southwest State University 2 (2012).  

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Mechanisms of Microwave Absorption in Carbon Compounds from Shungite

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