Conduction mechanisms study in CaCu2.8Ni0.2Ti4O12 ceramics sintered at different temperatures

Abstract

CaCu2.8Ni0.2Ti4O12 ceramics were prepared via the solid-state reaction. The pellets were sintering at 950 °C, 1000 °C, 1050 °C and 1100 °C for 24h. The X-ray diffraction (XRD) exhibits the crystallization of all the samples in the cubic structure with Im3‾ space group. The scanning electronic microscope (SEM) analysis show the growth of grain size by increasing sintering temperature from 0.65 to 18.58 μm. The conductivity analysis present a notable increase with the heating treatment. Both ac and dc electrical conductivity are fully examined as function of frequency and temperature. The ac conductivity discloses that correlated barrier hopping and non-overlapping small polaron tunneling models are the dominated conduction mechanisms existing in our compounds. By rising the sintering temperature the barrier height, above which jump the polarons or the electrons, tends to lower. The dc conductivity reveals that the conduction is achieved by the jump of polaron to the neighboring site and at variable distances.