摘要
THE composites formed by mixing metal particles into matrices have special optical and electri-cal properties. Up to now, main work has been laid on the investigation of optical propertyof the composites, rather than on that of electrical property. As well known, the structure of ZnO varistors can be described as semiconducting grainssurrounded by a thin layer of insulator. The thin layer of insulator is of electrical tunneling ef-fect leading to function of varistors. Because the resistance of the semiconducting grains
