Effect of variations in grain size and grain boundary barrier heights on the current-voltage characteristics of ZnO varistors

Throughout the microstructure at every varistor, there exist variations of the grain size and the electrical properties of the individual grain boundaries. To calculate the effect of such microstructural variations on the overall electrical transport properties, we describe a multibond percolation approach utilizing effective medium theory. The model presented takes into account these variations as well as the electrical conductivity of the ZnO grains themselves. To illustrate the predictions of the model, both the effect of continuous distributions in the grain boundary potential and the grain size are considered, as well as a bi-lognormal distribution in grain size to represent the effect of a population of anomalously large grains in a smaller grain size varistor.

[1]  M. Tao,et al.  Different ‘‘single grain junctions’’ within a ZnO varistor , 1987 .

[2]  G. Dunlop,et al.  The effect of Bi2O3 content on the microstructure and electrical properties of ZnO varistor materials , 1989 .

[3]  K. Eda,et al.  Grain growth control in ZnO varistors using seed grains , 1983 .

[4]  T. Gupta.  Application of Zinc Oxide Varistors , 1990 .

[5]  Blatter,et al.  Carrier transport through grain boundaries in semiconductors. , 1986, Physical review. B, Condensed matter.

[6]  Non-linear I-V characteristics of double Schottky barriers and polycrystalline semiconductors , 1992, cond-mat/9209020.

[7]  Mahan,et al.  Nonlinear currents in Voronoi networks. , 1995, Physical review. B, Condensed matter.

[8]  H. Philipp,et al.  Oxide Nonlinear Conductors: A Review , 1990 .

[9]  Hsin-Kai Wang,et al.  Averaging Effect on Current-Voltage Characteristics of ZnO Varistors. , 1995 .

[10]  J. V. Kemenade,et al.  Direct determination of barrier voltage in ZnO varistors , 1979 .

[11]  P. R. Emtage,et al.  Statistics and grain size in zinc oxide varistors , 1979 .

[12]  G. Pike.  Semiconductor grain-boundary admittance: Theory , 1984 .

[13]  D. Clarke.  The microstructural location of the intergranular metal‐oxide phase in a zinc oxide varistor , 1977 .

[14]  Nan Ce-wen.  THEORY OF CONDUCTION OF NONLINEAR ZnO CERAMICS (II) APPLICATION OF MODEL OF CONDUCTION , 1986 .

[15]  M. Matsuoka.  Nonohmic Properties of Zinc Oxide Ceramics , 1971 .

[16]  Nan Ce-wen.  THEORY OF CONDUCTION OF NONLINEAR ZnO CERAMICS (I)——THEORY OF MODEL OF CONDUCTION , 1986 .

[17]  Blatter,et al.  Electrical breakdown at semiconductor grain boundaries. , 1986, Physical review. B, Condensed matter.

[18]  H. R. Philipp,et al.  Theory of conduction in ZnO varistors , 1979 .

[19]  G. Blatter,et al.  REVIEW ARTICLE: Electrical properties of grain boundaries in polycrystalline compound semiconductors , 1990 .

[20]  R. Einzinger.  Grain junction properties of ZnO varistors , 1979 .

[21]  Influence of microstructural disorder on the current transport behavior of varistor ceramics , 1996 .