Electrical conductivity and CO gas sensitivity of ZnO-TiO2 composites

Using complex impedance measurement, a voltage-current source and measurement unit, the AC and DC characteristics of ZnO-TiO₂ composites are investigated. The electrical conductivity increase with increasing TiO₂ content was explained by the connectivity of ZnO and TiO₂ grains. Compared with pure and ball-milled ZnO, the electrical conductivity of TiO₂ added ZnO in the impedance spectrum is four orders of magnitude smaller. The calculated relative dielectric constants for the 3, 5, and 7 mol% TiO₂ added ZnO are 7, 13, and 120, respectively. Compared with the relative dielectric constant of ZnO, the semicircle of 3 mol% TiO₂ added ZnO seems to be the ZnO grain. The sizes of the semicircle decrease with increasing TiO₂ content. These results are consistent with the trends of DC conductivity