Effect of sintering conditions and doping type on the functional properties of ZnO semiconductors

Electrical properties and microstructure of ZnO ceramic bodies doped with a constant ratio of different dopants were studied under several of sintering conditions. The selected general chemical formula was (99Zn–M) where M=CuO, V2 O5 , MnO2 and GeO2 . The different compositions were processed by the conventional solid state reaction and fired at various temperatures between 1000 and 1300 °C for 1–3 h. The degree of sintering of the ZnO bodies was identified from the determination of the physical properties. The obtained results showed that, the optimum sintering conditions of ZnO varistors are either 1200 °C/3 h or 1300 °C/2 h. Both the electric modulus and dielectric loss tangent were studied as a function of frequency. The addition of CuO gave the maximum breakdown voltage, highest dielectric constant and the best electrical conductivity in the studied compositions. Also, the addition of V2 O5 gave the minimum dielectric loss, and therefore, the two samples could be used in different useful technological applications.