Dielectric abnormities in complex perovskite BaTi1-x (Co0.5Nb0.5) x O3 ceramics

Dielectric characteristics of BaTi1-x (Co0.5Nb0.5) x O3 (x=0.2, 0.4 and 0.6) ceramics are investigated together with mixed-valence structure. X-ray diffraction shows that all samples are cubic perovskite phase at room temperature. As the sintering temperature increases, grain size increases, accompanying obvious change in dielectric response. The samples with larger grains exhibit the giant dielectric characteristics, which are considered to be attributed to domain boundary effect. The frequency dependence of the loss peak is found to obey the Arrhenius law with an activation energy of ~0.3eV, which is assigned to be the result of charge ordering.