The electrical properties of semiconducting ceramic composites which were made from n-type ZnO and p-type CuO were investigated. The conductivity increased with increasing CuO contents of between 1 and 95mol%. The impedance response

exhibited 3 semicircles, thus indicating that 3 resistive elements contributed to the total resistance. A new model which was based upon the equivalent circuits was developed in order to explain the contribution which grain boundaries made to the resistance of the composite.

Composition Dependence of the Electrical Conductivity of ZnO(n)–CuO(p) Ceramic Composite. Jun, S.T., Choi, G.M.: Journal of the American Ceramic Society, 1998, 81[3], 695-9