Nonlinear currents in Voronoi networks

Current Localization, Non-Uniform Heating, and Failures of ZnO Varistors

“…The current distribution in the sample was found by just calculating separately the cnrrent in each path. The general predictions of this simple model agree with those of more realistic Voronoi network models [15]. The current localized in the paths with the least number of grain boundaries, or grains.…”

Modeling of electrical transport in Zinc Oxide varistors

“…Several numerical models have been proposed to describe electrical transport in varistors (Bartkowiak and Mahan, 1995;Vojta et al, 1996;Qingheng et al, 2002;Hofstaetter and Supancic, 2013). In these models, the varistor microstructure is first represented geometrically by a space filling mesh.…”

Percolation effects in dc degradation ofZnOvaristors

“…They are the effective medium approximation, 41,42 the network models based on Kirchhoff equations [43][44][45] and percolation theory approach. 34,[46][47][48] Using ideas of percolation, a phenomenological approach to nonOhmic conduction in ZnO varistor was developed and expression J ¼ 0 E expðEÞ (here J is the current density and E is the electric field) was obtained.…”

“…34,[46][47][48] Using ideas of percolation, a phenomenological approach to nonOhmic conduction in ZnO varistor was developed and expression J ¼ 0 E expðEÞ (here J is the current density and E is the electric field) was obtained. 49 The mentioned methods were used for the analysis of current-voltage (IðUÞ) characteristic 34,[41][42][43][44][45][46][47]49 and temperature dependence of conductivity 48 in ZnO varistor. However, application of such models to a study of degradation in varistor ceramics seems to be promising.…”