•Binary mapping of microscopic images of two-phase systems•Measuring the integral conductivity by the analysis of binary conductivity map•Measuring the content of the conductive /non-conductive phase ...by the conductivity map
The determination of the content of the conducting phase and the assessment of conductivity by microscopic images are interesting for rapid and non-destructive analysis of the electrophysical properties of two-phase (conductor/dielectric) samples during the atomic force microscopy. In this paper we summarized results of the analysis of the conductivity maps of the shungite surface by the method of discretization by applying a square grid with subsequent binary digital processing. Microstructure and conductivity were evaluated by measuring the average length of continuous conductive circuits isolated on the grid. A model was considered that established a unique correspondence (up to normalizing coefficients) between the length of the conductive circuits on the conductivity maps and the integral conductivity of the sample as a whole. An analytical equation was obtained that described such dependence with an accuracy of units of percent. We proposed a method for measuring the integral conductivity of a shungite samples based on an analysis of its binary conductivity map obtained by spreading resistance microscopy. This method can be used to determine the conductivity by surface conductivity mapping for shungite-like two-phase conductor/dielectric systems, and in general, for any two-phase substances where the phases differ in AFM-determined properties.
An algorithm is considered for the statistical analysis of images of nanoparticles obtained by scanning probe microscopy, based on the harmonic analysis of surface profiles with a complex relief. ...Using harmonic analysis, the average sizes of particles are determined and the sizes of their aggregates are estimated. The algorithm enables the analysis of large samples of particles; in this work, it is tested using model natural objects with an ordered and disordered arrangement of nanoscale particles. The dependence of the analysis results on the type of particle size distribution is also considered, and the features of determining the average size for Gaussian and logarithmically normal distributions are revealed. Among the possible applications of the algorithm, we can mention analysis of the average size of particles and the value of their aggregation in microdispersed and nanodispersed structures (thin amorphous films, colloidal systems, noncrystalline substances, polymers) based on three-dimensional or pseudo-three-dimensional microscopic images.
Abstract
The map of carbon distribution in the sample of graphene-containing shungite is investigated by the electron microscopy. It is found the large quantity of stacks which are formatted by ...parallel disposed layers of graphene. The model of electrical conductivity of graphene stack is proposed. This model takes into consideration the arbitrary orientation of layers relatively to the direction of current. It is made the numerical calculation of dependence of conductivity from the orientation of graphene layers. It is found the sharp abatement of conductivity by the orientation of graphene layers relatively to the current direction along the corner near the 45 degree. The obtained peculiarities are explained by the influence of geometrical factor.
The influence of graphene stacks on the formation of structural and electrical parameters of shungite carbon was determined. The spatial distribution map of graphene layers and stacks consisting of ...these layers was obtained by the STEM method. Statistical analysis of images of graphene stacks and the gaps between them was performed. Based on the data obtained, a simplified regular structure model is proposed, within the framework that allows one to quantitatively estimate the spatial dimensions of the carbon regions and describe the integral conductivity of shungite carbon.
A complex approach, which includes simultaneous data acquisition and processing, to analyze various physical parameters characteristics of the same sample cross-section at high resolution allows to ...extract information of much better quality and, thus, is a basis of modern studies at nanolevel. A concomitant investigation of surface topography and local electrical features of presumably defect-laden pseudomonocrystalline graphite is presented as an example. The structural state of graphite is monitored “in situ” using the microdiffraction unit of scanning electron microscope VEGA3 TESCAN and additionally tested by high resolution Raman spectroscopy measurements. The study reveals a previously undetectable by standard nanotopographic and X-ray diffraction observations nanostructure of pseudomonocrystalline graphite. A novel graphite-carbyne intergrowth model based on the energetically stable attachment of carbyne-like CC bonded chains to sp2 graphitic fragments is presented.
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We have studied different mineralogical objects: natural glasses of impact (tektites, impactites) and volcanic (obsidians) origin, using atomic force microscopy, X-ray microanalysis, infrared and ...Raman spectroscopy. The spectroscopy showed the difference in the structure and chemical composition of the glasses of different origin. The analysis of the dependence of nanoscale heterogeneity of the glasses, revealed by the atomic force microscopy, on their structural and chemical features was carried out.
Newly found impact vein-bodied ultrahigh pressure high temperature (UHPHT) glasses from Kara astrobleme (Russia) and impact drop-shaped glasses from Ries crater suevites (Germany) have been ...investigated. The nanostructure of the glasses has been analysed using atomic force microscopy (AFM) supported by a complex of optical microscopy, scanning electron microscopy (SEM) combined with EDS analysis, and Raman spectroscopy. The received data demonstrate the different levels of impact melt differentiation through partial crystallization and polymerization; the amorphous substance is presented by similar 60-80 nm globular nanostructural composition.
The paper presents the results of study of the carbon-containing phase discovered in the impact glass of the Kara astrobleme. We used the following research methods: optical, scanning electron, and ...atomic force microscopies, as well as Raman spectroscopy. This phase represents carbon-containing inclusions up to several tens of micrometres in size with an amorphous diamond-like structure. At the nanoscale, the studied phase is characterized mainly by a homogeneous structure.
The nanoporosity and structure of natural carbons has been investigated on the example of Karelian carbon-rich shungites by comparing the data of small-angle synchrotron radiation scattering and ...highresolution microscopy. The analysis of small-angle scattering data is based on the model of scattering spheres with lognormal size distribution. It is found that the structure of samples from the Maksovo and Zazhogino deposits subjected to high temperatures in the geological medium and (also to a lesser extent) a sample from the Shunga deposit can be described as an aggregation of polydisperse scattering spheres with lognormal size distribution; the characteristic scatterer size is determined for them. A comparison with microscopy data shows that these scatterers are mainly associated with pores, and the character of their size distribution is similar to that previously established for nanoglobules in schungites.
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