On estimation of mosaic block size and flake anisometry of artifical graphite by magnetoresistance

The article presents the results of mathematical modeling of the flow of electric current in a lamellar graphite polycrystal in a magnetic field. In contrast to the simple model, taking into account only the contact resistance between the scales, this model also takes into account the ohmic resistance along and across the layers of graphite based on the chain model of the flow of electric current in a polycrystal of graphite. As a result, a formula with refined correction coefficients was obtained, which allows one to choose polycrystal parameters for calculating the temperature dependence of the resistivity and magnetoresistance. A comparison is made with a simple model that takes into account only contact resistance, the difference is up to 50 % from the previous estimate. The difference is explained by the peculiarities of the connection of crystallites in a polycrystal. This allows analyzing the size of the crystallites and their connections in artificial graphite on the basis of its electrophysical properties.