Conduction mechanism and dielectric properties of ZnO/MgO solid composites

In this paper, (1−x)ZnO/xMgO solid composites, where x = 0, 10 and 20%, were prepared at high temperature 1200 °C by a solid-state method. The effect of increasing MgO content on structural, morphological, dielectric and the electrical properties of the ZnO/MgO composites has been investigated. The X-ray diffraction analysis indicates that all the samples have a prominent hexagonal crystalline structure with (002) and (101) as preferred growth directions and the segregation of MgO cubic phase took place for an MgO composition x ≥ 10 wt%. Analysis of infrared (IR) is in agreement with the diffraction results of X-ray diffraction. Morphological properties showed that the grain size was decreased with increasing MgO content. For the dielectric properties, a strong dispersion of permittivity constants was observed at low frequency, which can be attributed to interfacial relaxation. For the electrical properties, the frequency dependence of ac conductivity is interpreted in terms of Jonscher’s law. The ac electrical conduction in ZnO/MgO composites is analyzed by different processes, which can be attributed to several models, the hopping correlated barrier (CBH) for the undoped ZnO sample, and the hopping correlated barrier (CBH) and the overlapping large polaron tunneling model for both composites ZnO/MgO:10% and ZnO/MgO:20%.