Electrical Conductivity of Sintered Bodies of ZnO Doped with Al₂O₃

The electrical resistivity of sintered bodies of ZnO doped with Al2O3 was measured as a function of the sintering degree over the temperature range from 150°C to 700°C by using AC bridge.The effect of electrode on the resistivity of sintered bodies of ZnO is significant in case of two-probe method. It was confirmed that indium electrode gave rise to the most ohmic contacts among various metal electrodes investigated.From consideration of the activation energy, the mechanism of electronic conduction in the low temperature region is different from that in the high temperature region.In the low temperature region, the activation energy decreases with an increase of the sintering degree; finally the value reaching zero as for the well-sintered specimen. The effect of the sintering degree upon the resistivity is remarkable. The resistivity decreases about three orders of magnitude with increase in the sintering degree from 49% to 80%, which is far greater than the change in carrier concentration due to valency control mechanism. Therefore, property of the sintered bodies must be discussed especially in taking consideration of texture.In the high temperature region, on the other hand, the effect of the sintering degree on the activation energy and the resistivity is smaller than that in the low temperature region. It may be thought that there takes place an electronic conduction independent of the texture of the sintered bodies.