scholarly journals Application of independent-channel method for investigation of electrical conductivity of graphene-containing shungite.

2021 ◽  
Author(s):  
I.V. Antonets ◽  
◽  
E.A. Golubev ◽  
V.G. Shavrob ◽  
V.I. Shcheglov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Spatial Distribution ◽  
Current Flow ◽  
Specific Conductivity ◽  
Specific Electrical Conductivity ◽  
Parallel Connection ◽  
Raster Electron Microscopy ◽  
Current Flows

The independent channel method which is intended for the calculation of specific electrical conductivity of graphene-contained shungite is proposed and realized on practice. It is noted that the most important of shungite application is the creation of screen hawing large area which are able to block electromagnetic radiation in wide frequency range. The most important factor which determines the blocking properties of shungite is the specific electrical conductivity of its carbon part which is determined by the spatial distribution of carbon atoms. As a main method of carbon structure investigation is mentioned the high-resolution raster electron microscopy which allows from the surface of specimen to receive the card of distribution of graphene slides and graphene packets. The spatial factor which determines the shungite conductivity is large anisotropy of single graphene slide which reaches three orders and more in the cases along and across the slide. The proposed method independent channels takes into consideration the arbitrary orientation of graphene packets relatively to direction of current flow. As a basis of method is employing the card of carbon spatial distribution which is received by raster electron microscopy method. The card is divided by parallel channels which transverse dimension is near or slightly exceeds the typical dimension of graphene packet. The channels are divided to square blocks which sides are equal to width of channel. The whole resistance of channel is formed by the successive connection of individual resistances of blocks. The resistance of whole card is determined by parallel connection of channels or averaging of resistance of all channels and following filling the whole area of card. The first step of analysis is the determination of advantage orientation of slides inside of every blocks. On the basis of determined orientation the block is filled by periodic structure which period is equal to the width of graphene slide and neighbouring interval. As a parameter which determines the orientation is used the angle between advantage orientation of graphene slides and axis of current flow between contacts. Owing to symmetry of task in comparison of current direction the limited meanings of corner is 0 and 90 degree. It is established two principal different cases of orientation: first – when determining angle is less than 45 degree and second when this angle is more than 45 degree. In the first case the current flows along the stripe with large conductivity. In the second case the current flows across these stripes so as through the stripes with low conductivity. It is found the smooth dependence of block resistivity from the angle of strip orientation. For the characteristic of area which is filled graphene slides it is proposed the coefficient of filling which is determined by binary discretization method. On the basis of analysis of slides orientation and filling coefficients are calculated the resistance of individual blocks. The resistances of all channels of investigated card are proposed. By using two methods – parallel connection and averaging over all channels it is calculated the specific electrical resistance and specific electrical conductivity of material as a whole. It is found that the received values of specific conductivity exceed the determined in experiment value in several (to 10) times. For the coordination of calculated value with experimental value it is made the variation of specific resistances of graphene slides and intervals between its. It id found that the calculation by method of parallel connection of channels ensures several better coordination than method of averaging. It is shown that the resistance is improved in the first turn by the increasing the resistance of interval between slides. In the quality of possible reason of decisive role of interval it is proposed the observed in experiment sharp non-homogeneity of relative arrangement of graphene slides. It is discussed the possible courses of further development of work. As a most important task it is proposed the more circumstantial determination of statistical character of received results.

scholarly journals Investigation of electrical conductivity of graphene-contained shungite using the high-resolution scanning electron microscopy.

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
I.V. Antonets ◽  
◽  
E.A. Golubev ◽  
V.G. Shavrov ◽  
V.I. Shcheglov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Specific Resistance ◽  
Specific Conductivity ◽  
Relative Concentration ◽  
Carbon Distribution ◽  
Black And White ◽  
Current Flows ◽  
Carbon Component ◽  
Scanning Electron

The electrical conductivity of carbon component of graphene-contained shungite is investigated. The basis of this investigation is the statistic processing of carbon distribution cards which are obtained by high-resolution scanning electron microscopy. For the original card of carbon distribution it is proposed the method of building of contour card with following conversion its into binary card which consist of net from cells having black and white colours. The statistic analysis of repeating of binary card structure in the frame of selected region having square form. It is shown that the relative concentration of cells both colour in selected region by the increasing of its dimensions undertakes the scattering which increases when dimension of region is decreased. It is found the minimal dimension of region in which the deflection of relative concentration of cells of unit colour from the constant value of this concentration is not more then 20%. This dimension is received as flat-characteristic of middle-statistic block which relative properties repeats the relative properties of structure as a whole. From the conditions of isotropy of carbon component of shungite the space model of symmetrical along three axis cubic middle-statistic block which consist of cubic cells both colours. It is established that black cells correspond to large conductivity and white cells correspond to small conductivity. In connection with the direction of electric current which flows along the flat of card it is proposed two kinds of graphene packets orientation. In this case the black cells having large conductivity are identified with graphene packets where the current flows along the graphene slides and the white cells having small conductivity are identified with graphene packets where the current flows across the graphene slides. For the analysis of conductivity of middle-statistic block the model of current tubes is proposed. From the whole structure of block the two kinds of tubes are selected. This kinds of tubes correspond to different cases of alternate with each other black and white cells. The structure of these tubes is identified with the set of favourable and non-favourable oriented graphene packets. On the basis of known resistances of graphene slide it is calculated the resistances of packets having favourable and non-favourable orientations. Using this resistances of packets the resistances of tubes are calculated. It is shown that the main role in resistance of tubes formation plays the resistance of intervals between graphene slides and graphene packets. Using obtained resistances of tubes it is found the resistance of middle-statistic block which has the parallel connections of tubes. On the basis of middle-statistic block resistance it is found the specific resistance and the back proportional to this resistance the specific conductivity of carbon component of shungite. It is shown that the main parameter which determines the resistance and conductivity is the specific resistance of interval between graphene slides and graphene packets. It is execute the comparison of determined specific conductivity with the observed in experiments specific conductivities of shungite received from different natural deposits. The some practical remarks and some little defects are proposed. The possibilities of improvement of proposed model are discussed.

scholarly journals A Method For Determination Of Specific Electrical Resistance Of Steel And Nano-Coating Sputtered On It

2015 ◽  
Vol 2 ◽  
pp. 118 ◽  
Author(s):  
Andris Martinovs ◽  
Josef Timmerberg ◽  
Konstantins Savkovs ◽  
Aleksandrs Urbahs ◽  
Paul Beckmann
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Permeability ◽  
Electrical Resistance ◽  
Skin Effect ◽  
Specific Electrical Resistance ◽  
Specific Electrical Conductivity ◽  
Relative Magnetic Permeability ◽  
Nano Coating ◽  
Cylindrical Steel

The paper describes methods developed to determine specific electrical conductivity and relative magnetic permeability of cylindrical steel items and nano-coatings deposited on them by sputtering. Research enables development of a new method for determination of thickness of vacuum deposited nano- coating that is based on application of skin effect.

DETERMINATION OF THE WAX LAYER ULTRASTRUCTURE OF JONAGOLD WITH CONFOCAL AND RASTER ELECTRON MICROSCOPY

2000 ◽  
pp. 389-396
Author(s):  
E.A. Veraverbeke ◽  
B. Nicolaï ◽  
P. Van Oostveldt ◽  
J. De Baerdemaeker
Keyword(s):  
Electron Microscopy ◽  
Raster Electron Microscopy

Determination of the electrical conductivity of human liver metastases: impact on therapy planning in the radiofrequency ablation of liver tumors

2016 ◽  
Vol 58 (2) ◽  
pp. 164-169 ◽  
Author(s):  
Urte Zurbuchen ◽  
Franz Poch ◽  
Ole Gemeinhardt ◽  
Martin E Kreis ◽  
Stefan M Niehues ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Radiofrequency Ablation ◽  
Liver Metastasis ◽  
Liver Metastases ◽  
Liver Tissue ◽  
Colorectal Liver Metastases ◽  
Liver Tumors ◽  
Tissue Temperature ◽  
Specific Electrical Conductivity

Background Radiofrequency ablation is used to induce thermal necrosis in the treatment of liver metastases. The specific electrical conductivity of a liver metastasis has a distinct influence on the heat formation and resulting tumor ablation within the tissue. Purpose To examine the electrical conductivity σ of human colorectal liver metastases and of tumor-free liver tissue in surgical specimens. Material and Methods Surgical specimens from patients with resectable colorectal liver metastases were used for measurements (size of metastases <30 mm). A four-needle measuring probe was used to determine the electrical conductivity σ of human colorectal liver metastasis (n = 8) and tumor-free liver tissue (n = 5) in a total of five patients. All measurements were performed at 470 kHz, which is the relevant frequency for radiofrequency ablation. The tissue temperature was also measured. Hepatic resections were performed in accordance with common surgical standards. Measurements were performed in the operating theater immediately after resection. Results The median electrical conductivity σ was 0.57 S/m in human colorectal liver metastases at a median temperature of 35.1℃ and 0.35 S/m in tumor-free liver tissue at a median temperature of 34.9℃. The electrical conductivity was significantly higher in tumor tissue than in tumor-free liver tissue ( P = 0.005). There were no differences in tissue temperature between the two groups ( P = 0.883). Conclusion The electrical conductivity is significantly higher in human colorectal liver metastases than in tumor-free liver tissue at a frequency of 470 kHz.

When Current Does Not Follow Bonds: Current Density in Saturated Molecules

2019 ◽  
Author(s):  
Anders Jensen ◽  
Marc Hamilton Garner ◽  
Gemma C. Solomon
Keyword(s):  
Spatial Distribution ◽  
Current Density ◽  
Current Flow ◽  
Structure Property ◽  
Conjugated Molecules ◽  
Structure Property Relationships ◽  
Electron Transport Properties ◽  
Current Flows ◽  
Molecular Conductance ◽  
Insight Into

<div> <div> <div> <p>The tools commonly used to understand structure-property relationships in molecular conductance, inter-atomic currents and conductance eigenchannels, generally give us a sense of familiarity, with the chemical bonding framework and molecular orbitals reflected in the current. Here we show that while this picture is true for conjugated molecules, it breaks down in saturated systems. We investigate the current density in saturated chains of alkanes, silanes and germanes and show that the current density does not follow the bonds, but rather the nuclei define the diameter of a pipe through which the current flows. We discuss how this picture of current density can be used to understand details about the electron transport properties of these molecules. Understanding the spatial distribution of current through molecules, rather than simply the magnitude, provides a powerful tool for chemical insight into physical properties of molecules that are related to current flow. </p> </div> </div> </div>

scholarly journals Application of decomposition method for calculation of electrical conductivity of shungite based on the electron-microscopic cards of carbon distribution.

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
I.V. Antonets ◽  
◽  
E.A. Golubev ◽  
V.G. Shavrov ◽  
V.I. Shcheglov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Specific Resistance ◽  
Specific Conductivity ◽  
Specific Electrical Conductivity ◽  
Contact Method ◽  
Carbon Distribution ◽  
Conducting Phase ◽  
Flat Area ◽  
Black And White ◽  
Shungite Carbon

The outlook of using the shungite for covering large area which can protect something from electromagnetic radiation is described. As a main parameter which determines the efficiency of created screens is determined the specific electrical conductivity of shungite carbon. For the measuring of conductivity it is proposed to use the high-resolution raster electron microscopy which make be possible to obtain the card of carbon distribution in the scale of some nanometers. The method of binarization of this card is proposed. This binare card describes the spatial distribution of two phases – large-conducting and small-conducting. The large-conducting phase consist of graphene slides. The small-conducting phase consist of chaotic distributed atoms of carbon. On the basis of binare card it is constructed the flat-area block which is looked as net from square cells having two colours – black and white which correspond one by one to large and small-conducting phases. On the area of block it is selected tubes of current which consist of straight chains of black and white cells connected in succession. The whole resistance of block is determined by parallel connection of these tubes. It is proposed the procedure of constructing this symmetrical block along two coordinates. The scheme of this construction is proposed. The calculation of block resistivity along two coordinates is executed. On the basis of flat-area block it is constructed the space elementary block which has equal to each other resistance along three coordinates. For the determination of specific resistance of material as a whole it is carried out the procedure of decomposition which consist of presentation the unit volume of specimen as a set of elementary blocks. For the real specimens of shungite from two natural deposits it is made the calculation of specific resistance and specific conductivity of shungite carbon. It is established that the calculated data are coincide with data received by contact method in the accuracy of 30%. As a most advantage of proposed method it is established the possibility of conductivity measuring of carbon part of shungite in the scale of some units of nanometers.

Analytical description of sodium halogenides melts specific electric conductivity and its calculation for sodium astatide melt

2019 ◽  
Vol 60 (12) ◽  
pp. 125-132
Author(s):  
Ivan K. Garkushin ◽  
◽  
Olga V. Lavrenteva ◽  
Karina R. Gilmanova ◽  
Yana A. Andreeva ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Comparative Analysis ◽  
Ionic Radius ◽  
Specific Conductivity ◽  
Analytical Description ◽  
Specific Electrical Conductivity ◽  
Specific Electric Conductivity ◽  
Straight Line ◽  
Direct Equation ◽  
The Individual

The paper presents analytical and graphical dependences of the individual haloganides melts specific electrical conductivity æ of the sodium NaHal series (Hal – F, Cl, Br, I) on the halogen order number Z, ionic radius r of haloganide-ion Hal–, halogen ionic potential 1/r, reduced ionic radius r/Z, difference of electronegativity (∆χ = χ(Hal) – χ(Na)): æ = f(Z); æ = f(r); æ = f(1/r); æ = f(r/Z); æ = f(∆χ) for the temperature higher melting temperatures on 5, 10, 50, 75, 100, 150 и 200°. M.Kh. Karapetyans сomparative methods were applied for the description. The minimum standard deviation and maximum correlation coefficient corresponds to the equation æ–1 = a + bexp1/r, according to which the numerical values of æ(NaAt) are calculated for real temperatures. The temperature dependence æ of the NaAt melt is described by the equation æ = 0.0508+0.0023Т. A comparative analysis of the relationship between the specific electrical conductivity of NaHal melts at a temperature of Tm + n (n = 10 ... 200° higher the melting temperature) and æ at (Tm + 5°). A comparative analysis is represented by straightforward dependencies. It was shown that the specific electrical conductivity of the NaAt melt is related to the electrical conductivity of LiAt by the direct equation æ(NaAt) = 0.035+0.607æ(LiAt). The straight line equationalso relates æ of the NaHal melt (Hal – F, Br, I, At) to the specific conductivity of the NaCl melt. Between the numerical values of the specific electrical conductivity of the sodium astatide (NaAt) melt calculated by different methods, consistent data were obtained.

When Current Does Not Follow Bonds: Current Density in Saturated Molecules

2019 ◽  
Author(s):  
Anders Jensen ◽  
Marc Hamilton Garner ◽  
Gemma C. Solomon
Keyword(s):  
Spatial Distribution ◽  
Current Density ◽  
Current Flow ◽  
Structure Property ◽  
Conjugated Molecules ◽  
Structure Property Relationships ◽  
Electron Transport Properties ◽  
Current Flows ◽  
Molecular Conductance ◽  
Insight Into

<div> <div> <div> <p>The tools commonly used to understand structure-property relationships in molecular conductance, inter-atomic currents and conductance eigenchannels, generally give us a sense of familiarity, with the chemical bonding framework and molecular orbitals reflected in the current. Here we show that while this picture is true for conjugated molecules, it breaks down in saturated systems. We investigate the current density in saturated chains of alkanes, silanes and germanes and show that the current density does not follow the bonds, but rather the nuclei define the diameter of a pipe through which the current flows. We discuss how this picture of current density can be used to understand details about the electron transport properties of these molecules. Understanding the spatial distribution of current through molecules, rather than simply the magnitude, provides a powerful tool for chemical insight into physical properties of molecules that are related to current flow. </p> </div> </div> </div>

scholarly journals Electrical conductivity test for Serbian spruce seed quality estimation

2005 ◽  
pp. 127-133 ◽  
Author(s):  
Vladan Ivetic ◽  
Jelena Milovanovic
Keyword(s):  
Electrical Conductivity ◽  
Tree Species ◽  
Seed Quality ◽  
Germination Rate ◽  
Statistical Significance ◽  
Specific Electrical Conductivity ◽  
Model Species ◽  
Quality Estimation ◽  
Serbian Spruce

In this paper, for the firs time in our country, electrical conductivity test was used for seed quality estimation. Since this test is not standardized for most of tree species, main goal of this paper was to investigate possibility of its use for estimation of potential germination rate of Serbian spruce seed, like model species. Negative correlation with great statistical significance (r=-0.9003) was found between specific electrical conductivity and germination rate. On this basis, authors were give proposal for determination of Serbian spruce seed quality, after measuring of electrical conductivity. Results show great potential of this method for seed quality estimation, and justify further work on its standardization for Serbian spruce, and other tree species as well.

Electrical Conductivity of Molten Carbonate and Carbonate–Chloride Systems Coexisting with Aluminium Oxide Powder

2017 ◽  
Vol 73 (1) ◽  
pp. 79-83 ◽  
Author(s):  
Elena V. Nikolaeva ◽  
Andrey L. Bovet ◽  
Irina D. Zakiryanova
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Specific Conductivity ◽  
Aluminium Oxide ◽  
Specific Electrical Conductivity ◽  
Impedance Method ◽  
Molten Carbonate ◽  
Composite Electrolytes ◽  
Two Phase ◽  
Oxide Concentration

AbstractThe electrical properties of composite electrolytes (suspensions) composed of α-Al2O3 powder and molten carbonate eutectic (Li2CO3–Na2CO3–K2CO3)eut or molten carbonate–chloride mixture 0.72(Li2CO3–Na2CO3–K2CO3)eut–0.28NaCl have been investigated by AC impedance method. This system shows a dependence of the electrical conductivity upon the temperature and the α-Al2O3 content. The specific electrical conductivity of the α-Al2O3/(Li2CO3–Na2CO3–K2CO3)eut system can be adequately described by the Maxwell equation for two-phase heterogeneous materials. The regression equation for the dependence of the specific conductivity of the α-Al2O3/(Li2CO3–Na2CO3–K2CO3)eut composite on the aluminium oxide concentration and temperature was obtained.

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