Electrical conductivity study in pure and doped ZnO ceramic system

We report here the electrical conductivities measurements of Zn1-xFexO ceramic samples with various x values (0.00 <= x <= 0.50). The measurements are made in both high and low temperature cases (300K <= T <= 523K) and (20K <= T <= 300K), respectively. Furthermore, the electrical conductivity data are well enough to calculate the activation energies E-a for the considered samples. The character of the conductivities curves is not absolutely symmetric to the response of temperature in both cases. Interestingly, two jumps are observed only in the conductivity curves at low temperatures. The onset temperatures of these jumps are increased by Fe up to 0.30, followed by a decrease at Fe = 0.50. At constant Fe content, the conductivities are found to be increased over the temperature range in both cases. While, these values are decreased with the increase in the Fe content up to Fe = 0.50. The conductivity character is divided into discrete regions over the temperature range corresponding to different activation energies. In high temperature case, the values of E. are increased with increasing Fe up to 0.30, followed by a decrease at 0.50. While, in low temperature cases, the values of E. are generally increased with increasing Fe up to 0.50. Our results are discussed in terms of potential barrier, donor concentration, point defects and adsorption-desorption of oxygen which are affected by Fe doping in ZnO ceramic system. (C) 2009 Elsevier B.V. All rights reserved.