Abstract:
Granular compounds consisting of conductive micro or nano inclusions located in a dielectric matrix exhibit a number of unusual properties, the origin of which is directly related to the ratio of conductive and non-conductive bulk phases. In the present work, to predict the electrical properties of a granular solid based on manganite La$_{1-x}$A$_x$MnO$_3$. (where A is a divalent element), an approximation model of a heterophase structure - effective medium has been adapted, which essentially represents a synthesis of the effective medium method and the percolation theory. Analysis of transport behavior within the framework of this model showed that the effective electrical conductivity of the granular medium increases significantly with an increase in the proportion of the volume occupied by the core of the granule relative to the volume of the intergranular space and the surface layer. The results obtained in the work are in good agreement with the experimental data for ceramic samples of manganite La$_{1-x}$A$_x$MnO$_3$.
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