A random resistor model to forecast the electrical properties of crystalline ionic conductor composites

A model able to forecast the electrical properties of crystalline composite s is presented. Systems having both insulating and ionic conducting phases were simulated taking into account the relative size and distribution of th e particles. The model works through three steps: a suitable digital image- based representation of the material microstructure, its conversion into a 3-D electrical network and the impedance calculation. The polycrystalline m icrostructure of the matrix was generated using the Voronoi tessellation an d the insulating phase was successively distributed along intergranular pos itions by a Montecarlo method. The simulated digital image was converted in a network of cubes and their edges substituted with discrete circuits. Suc h a procedure was pet formed by well defined rules; so the bulk and the gra in boundary electrical behaviour of the different phases was reproduced. Th e electrical network thus attained was solved via a transfer-matrix method and the complex impedance spectra obtained. The model might be used to tail or the composites in order to obtain the best compromise between its electr ical properties and microstructure. (C) 2000 Elsevier Science BN. All right s reserved.