Investigation of electrical conductivity of graphene-contained shungite using the high-resolution scanning electron microscopy.
Authors:   Syktyvkar State University, Oktyabrskiy prosp. 55, Syktyvkar 167001, Russia, Antonets I.V. , Golubev E.A. ,   Geology Institute Komy SC UrD RAS, Pervomaiskaya 54, Syktyvkar 167982, Russia, Shavrov V.G. ,   Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Mokhovaya 11-7, Moscow 125009, Russia, Shcheglov V.I. ,   Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Mokhovaya 11-7, Moscow 125009, Russia
Published: April 2021

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.