scholarly journals The influence of carbon component structure of graphene containing shungite on its electrical conductivity.

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
I.V. Antonets ◽  
◽  
E.A. Golubev ◽  
V.G. Shavrov ◽  
V.I. Shcheglov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Spatial Orientation ◽  
Periodic Structures ◽  
Specific Conductivity ◽  
Contact Method ◽  
Equal Concentration ◽  
Component Structure ◽  
Lateral Projection ◽  
Incomplete Filling ◽  
Carbon Component

The investigation of the influence of carbon component structure of graphene containing shungite on its electrical conductivity is carried out. Five shungite samples from three different deposits with the same carbon content equal to 97% were selected as the object of research. It is established that the integral conductivity of specimens which is measured by four-contact method is changed in frames from 600 Sm/m to 2500 Sm/m. For the interpretation of so large scattering of data by equal concentration it was undertaken the investigation of carbon component structure on nano-level which was made by method of high-distinguish raster electron microscopy. By this method on the microscopic section of these specimens was obtained the cards of surface distribution of graphene slides and graphene packets. For the analysis of conductivity of specimens on the basis of these cards it was employed the method of independent channels. This method employs the presentation of specimen as a combination from parallel current-leading channels with following distribution of channel to cubic space blocks. The successive connection of blocks with accounting of slides orientation determines the total resistance of each channel and the parallel connections of all channels determines the specific conductivity of specimen as a whole. For the obtaining the quantity characteristics the whole card was distributed to some more small regions – fields. In this case the obtained results are averaged by the whole square of card. For the analysis of the field the method of square discretization was used. By this method the whole field id distributed to individual squares which dimension is near to the dimension of graphene packet. It was established that the character of structure in each square has two variants: first when the slides of graphene has clear determined spatial orientation ant the second when special orientation is absent and by orientation the squares are neutral. It is made the quantity analysis of neutral squares along the all specimens. It is shown that the normalized quantity of neutral squares is straight proportional to specific conductivity of specimen. The analysis of slides graphene orientation in squares with clear determined spatial orientation is carried out. For investigation of space structure of channel, the square was identified with lateral projection of block along two coordinates. The dependence of block resistance from the slide orientation is found. It is shown that the block resistance by the flowing of current across the graphene slides is more than order exceeds the resistance by the flowing of current along the slides of graphene. It is shown that the most role in formation of channel resistance play the blocks which graphene slides are oriented across the current flowing. By the adding of channels along the structure of volume unit it was founded the specific conductivity of specimen as a whole. It is established that the obtained meanings of conductivity for all specimens exceed the obtained by contact method on several times. As a reason of this exceeding it is established the absence of accounting the influence of enough small conductivity of intervals between slides and packets and also the absence of accounting of incomplete filling of squares by periodic structures. It is shown that the optimal in plane of correspondence to experiment is the introduce the normalization coefficient of conductivity of intervals which is equal to 0,2222. For the accounting of incomplete filling of squares by periodic structures it was carried out the binary discretization of most typical blocks with the resolution near 0,2 nm which is near the thickness of graphene slide. Along the obtained selection there was the averaged coefficients of filling of carbon which are equal from 0,10 to 0,15 parts for the whole volume of blocks. With the normalized conductivity of intervals and coefficients of filling of blocks it was found the integral conductivity for all specimens. It is shown that the obtained values are near the measured by contact method in the precision not more than 37%. In brief it is discussed the quality reason of apparent paradoxical increasing of integral conductivity by decreasing on structural character of carbon. It is established that the main reason of this increasing is the decreasing of contribution of graphene slides having large resistance which are oriented across the flowing of current.

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.

scholarly journals INFLUENCE OF CONDUCTIVE POLYMER FILLER ON ELECTRICAL CONDUCTIVITY AND MICROHARDNESS OF COMPOSITES WITH DIELECTRIC POLYMERIC MATRICES

2020 ◽  
Vol 2020 (60) ◽  
pp. 14-21
Author(s):  
Galyna MARTYNІUK ◽  
◽  
Olena AKSIMENTYEVA ◽  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Conjugated Polymers ◽  
Polymer Matrix ◽  
Specific Conductivity ◽  
Conductive Polymer ◽  
Polymer Matrices ◽  
Material Strength ◽  
Contact Method ◽  
Polymer Filler

Nowadays special attention is given to the so-called “smart-materials” or “intellectual” materials, which have the ability to purposefully change their physical and physical-chemical properties depending on changing external conditions. Conductive conjugated polymers–polyaniline (РАNi) and its derivatives may alter their properties in response to external action–exhibit sensory sensitivity, electrochromic, thermochromic and solvatochromic effects. When creating РАNi composites with industrial polymer matrices, an important issue is to determine the physical and mechanical properties, in particular, the microhardness as a material strength characteristic. The composite samples were obtained by the method of thermal pressing of highly dispersed powders of the conductive polymers dispersed in the polymer matrices. The mechanical properties of the composites were studied by the method of measuring microhardness and boundary microhardness on a Heppler consistometer. The determination of the electrical conductivity of the composites in the molded samples was determined by the standard 2-contact method at a temperature T = 293 K. The influence of the acid doped polyaniline (РАNi) as a conductive polymer filler on the microhardness of composites with polymer matrices of different structure (polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), polybuthyl methacrylate (PBMA), epoxy resin ED-20) was studied. It is found that the nature of the interaction between the polymer matrix and the conductive polymer filler depends on its content and the structure of the matrix, which is manifested in the growth of microhardness for composites PBMA–РАNi and ED-20−РАNi and its reduction for composites PVA–РАNi at the contents of the filler 5−20 %. The dielectric polymer matrix preserves the properties inherent in both high polymers (high elasticity, thermoplasticity) and the semiconductor nature of the electrical conductivity inherent in the conjugated polymers. The value of the specific conductivity of the composites obtained well correlated with changes in microhardness, which is a confirmation of the enhancing or loosening nature of the interaction between the polymer matrix and the conductive polymeric filler.

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.

Influence of conductive polymer filler on electrical conductivity and microhardness of composites with dielectric polymeric matrices

2019 ◽  
pp. 80-86
Author(s):  
G. V. Martyniuk ◽  
O. I. Aksimentyeva
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Conjugated Polymers ◽  
Polymer Matrix ◽  
Specific Conductivity ◽  
Conductive Polymer ◽  
Polymer Matrices ◽  
Material Strength ◽  
Contact Method ◽  
Polymer Filler

Nowadays special attention is given to the so-called "smart-materials" or "intellectual" materials, which have the ability to purposefully change their physical and physical-chemical properties depending on changing external conditions. Сonductive conjugated polymers - polyaniline (РАNi) and its derivatives may alter their properties in response to external action - exhibit sensory sensitivity, electrochromic, thermochromic and solvachromic effects. When creating РАNi composites with industrial polymer matrices, an important issue is to determine the physical and mechanical properties, in particular, of microhardness as a material strength characteristic. Composite samples were obtained by the method of thermal pressing of highly dispersed powders of conductive polymers dispersed in polymer matrices. The mechanical properties of the composites were studied by the method of measuring microhardness and boundary microhardness on a Heppler consistometer. The determination of the electrical conductivity of the composites in the molded samples was determined by the standard 2-contact method at a temperature T = 293 K. The influence of the acid doped polyaniline (РАNi) as an conductive polymer filler оn on the microhardness of composites with polymer matrices of different structure (polyvinyl alcohol (PVA), polymethylmethacrylate (PMMA), polybuthylmethacrylate (PBMA), epoxy resin ED-20) was studied. It is found that the nature of the interaction between the polymer matrix and the conductive polymer filler depends on its content and the structure of the matrix, which is manifested in the growth of microhardness for composites PBMA – РАNi and ED-20 - РАNi and its reduction for composites PVA– РАNi at the contents of the filler 5-20 %. The dielectric polymer matrix preserves the properties inherent in both high polymers (high elasticity, thermoplasticity) and the semiconductor nature of the electrical conductivity inherent in the conjugated polymers. The value of the specific conductivity of the composites obtained well correlated with changes in microhardness, which is a confirmation of the enhancing or loosening nature of the interaction between the polymer matrix and the conductive polymeric filler.

Electrical Conductivity of Magnesium Oxide/Molten Carbonate Eutectic Coexisting System

2019 ◽  
Vol 74 (9) ◽  
pp. 739-742
Author(s):  
Elena V. Nikolaeva ◽  
Andrey L. Bovet ◽  
Irina D. Zakiryanova
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Magnesium Oxide ◽  
Solid Phase ◽  
Specific Conductivity ◽  
Maxwell Model ◽  
Impedance Method ◽  
Molten Carbonate ◽  
Carbonate Ions ◽  
Alkali Carbonate

AbstractThe electrical conductivity of molten ternary alkali carbonate eutectic, coexisting with MgO particles, has been investigated. The conductivity was measured by the AC impedance method. The apparent activation energy ΔEa increased with the MgO content. This fact can be attributed to the effect of the solid phase. The specific conductivity of those systems could not be described using the Maxwell model over the solvation process of the carbonate ions on the particles of the magnesium oxide.

scholarly journals Multicomponent non-aqueous electrolytes for high temperature operation of supercapacitors

2020 ◽  
Vol 61 (1) ◽  
pp. 67-75
Author(s):  
Mikhail V. Astakhov ◽  
◽  
Ludmila A. Puntusova ◽  
Ruslan R. Galymzyanov ◽  
Ilya S. Krechetov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Propylene Carbonate ◽  
Boiling Point ◽  
Elevated Temperatures ◽  
Specific Conductivity ◽  
Ethylene Carbonate ◽  
Aqueous Electrolytes ◽  
Cyclic Carbonates ◽  
High Boiling Point

Multicomponent non-aqueous electrolytes based on cyclic carbonates and tetraethylammonium tetrafluoroborate have been developed for the operation of supercapacitors at elevated temperatures. Propylene carbonate, which has a high dielectric constant and a high boiling point, was used as the main solvent of electrolytes. However, a significant drawback of propylene carbonate is its high viscosity, which leads to decrease in the electrical conductivity of electrolytes based on it compared to electrolytes based on acetonitrile. To increase the electrical conductivity, an additional component was introduced into the electrolyte – a cosolvent with the necessary set of properties. When choosing cosolvents, two approaches were used. In the first case, to increase the dielectric permittivity of the liquid phase, ethylene carbonate having a higher dielectric constant than propylene carbonate was introduced into the electrolyte. This approach made it possible to significantly increase the electrical conductivity of the electrolyte and to achieve high resource stability of the supercapacitor. The values of the specific capacitance and energy of the supercapacitor with the introduction of ethylene carbonate in the electrolyte practically did not change. In the second case, butyl acetate, which has a low viscosity but has a moderate polarity and a sufficiently high boiling point, was used as a co-solvent. In this case, not only an increase in the electrical conductivity of the electrolyte was observed, but also a significant increase in the capacitive characteristics of the supercapacitor. It is shown that the use of a mixture of cyclic carbonates and esters as a solvent in the composition of the electrolyte can increase its specific conductivity by 40%, and the specific energy consumption of a supercapacitor by 20%. The developed electrolytes provide long-term operation of supercapacitors both at room temperature and at elevated temperatures up to 80 °С.

scholarly journals CAPACITIVE PROPERTIES OF MODIFIED AND NON MODIFIED THERMALLY EXPANDED GRAPHITE COMPOSITES WITH POLYANILINE

2020 ◽  
Vol 2020 (60) ◽  
pp. 75-84
Author(s):  
Yaroslav KOVALYSHYN ◽  
◽  
Ivanna TERENYAK ◽  
Orest PEREVIZNYK ◽  
◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrochemical Method ◽  
Specific Conductivity ◽  
Expanded Graphite ◽  
Conditional Density ◽  
Thermally Expanded Graphite ◽  
Graphite Content ◽  
Capacitive Properties ◽  
Thermally Exfoliated Graphite ◽  
Graphite Composites

Modified thermally exfoliated graphite with p-nitrophenyldiazonium tetrafluoroborate, followed by reduction of nitrophenyl groups to aminophenyl ones. Composites PAN - graphite, PAN - modified graphite at a constant value of potential 1 V were synthesized by electrochemical method. Their conditional density and electrical conductivity were determined. The electrochemical behavior in 1 M HCl solution was investigated and the capacity of synthesized composites was calculated. The conditional density of PAN composites with modified and non modified graphite increases sharply with increasing graphite content from 0 to 5%. At graphite contents higher than 5%, the density of composites varies very slightly. In the range of graphite contents 0% - 20%, the density is the highest for composites with a graphite content of 5% - 10%. In the case of modified graphite, the density of composites is higher than that of composites with non modified graphite. Analysis of the dependence of the specific conductivity on the content of modified graphite indicates that the conductivity of PAN - graphite composites increases the most with increasing graphite content from 1 to 10%. In this interval, the conductivity increases linearly. This indicates the absence of specific interactions between the components in the synthesized composites, as well as the fact that the nature of the distribution of these components does not change with changes in the graphite content. For a composite with modified graphite, there are two maximum capacities of composites with a graphite content of 2 and 10%. For a composite with non modified graphite on the obtained curves there is a maximum capacity of composites with a graphite content of 2%. Modification of the graphite surface leads to increased interaction between the components of the compo¬site, which resulted in the compaction of its structure. As a result, the capacitive characteristics of modified graphite composites, as well as CVA currents and electrical conductivity, were lower compared to composites with non modified graphite.

scholarly journals Electrochemical evidences of the protection efficiency of propargyl alcohol o low-carbo steel in ethanolic solutions by electrical conductivity measures

1993 ◽  
Vol 15 (15) ◽  
pp. 45
Author(s):  
Reinaldo Simões Gonçalves ◽  
Natalie Maria Coradini
Keyword(s):  
Electrical Conductivity ◽  
Specific Conductivity ◽  
Low Carbon Steel ◽  
Conductivity Measurement ◽  
Good Method ◽  
Propargyl Alcohol ◽  
Low Carbon ◽  
Electrical Conductivity Measurement ◽  
Corrosion Reaction ◽  
Conductivity Measures

It is shown that electrical conductivity measurement is a good method to characterize corrosion processes that occur on low-carbon steel in ethanolic solutions. Different aggressive coonditions were tested by changing the water content in distilled ethanol and by adding acid. Propargyl a alcohol inhibits the corrosion reaction. The specific conductivity of the solution decreases in the presence of propargyl alcohol for varying levels of aggressiveness. In dilute acetic acid ethanolic solutions, the proyection efficiency was better in 1.0mM propargyl alcohol than in the other concentrations.

Structure Sensitive Properties of System B2O3- CaO Melts

2020 ◽  
Vol 400 ◽  
pp. 186-192
Author(s):  
A.S. Vusikhis ◽  
Evgeny N. Selivanov ◽  
A.N. Dmitriev ◽  
V.P. Chentsov ◽  
V.V. Ryabov
Keyword(s):  
Electrical Conductivity ◽  
Surface Tension ◽  
Boron Oxide ◽  
Liquidus Temperature ◽  
Contact Method ◽  
Structure And Properties ◽  
Density Measurements ◽  
Structure Sensitive ◽  
Metallurgical Processes ◽  
Borate Melts

Boron oxide-based systems on structure and properties are similar to silicate systems, but they are more fusible and so are widely used in modelling various metallurgical processes. This paper presents the results of viscosity, electrical conductivity, surface tension and density measurements of the B2O3–CaO system with a content of 25–45% CaO in the temperature range above the liquidus temperature. To measure viscosity, vibration viscometry was used. Electrical conductivity was measured via the contact method using an alternating current bridge. Surface tension and density were measured using the lying drop method. The obtained results were used to describe the structure of borate melts.

Apparatus for Measuring the Swelling Dependent Electrical Conductivity of Charged Hydrated Soft Tissues

2002 ◽  
Vol 124 (6) ◽  
pp. 790-793 ◽  
Author(s):  
W. Y. Gu ◽  
M. A. Justiz
Keyword(s):  
Electrical Conductivity ◽  
Articular Cartilage ◽  
Water Content ◽  
Linear Correlation ◽  
Soft Tissues ◽  
Specific Conductivity ◽  
Bovine Articular Cartilage ◽  
Significant Linear Correlation ◽  
New Apparatus ◽  
Phosphate Buffered Saline

This paper describes a new apparatus and method for measuring swelling dependent electrical conductivity of charged hydrated soft tissues. The apparatus was calibrated using a conductivity standard. Swelling dependent specific conductivity of porcine annulus fibrosis (AF) samples was determined. The conductivity values for porcine AF were similar to those for human and bovine articular cartilage found in the literature. Results revealed a significant linear correlation between specific conductivity and water content for porcine AF tissues tested in phosphate buffered saline (PBS).

Sign in / Sign up

Export Citation Format

Share Document