Electrical resistance transition of CaCu3Ti4O12 ceramics induced by cyclic voltammetry conditioning

Compared with traditional ferroelectric materials sintered by two steps, CaCu3Ti4O12 is regarded as a promising dielectric material attributed to its huge dielectric constant, temperature stability, and more easily sintered by only one step through solid-state reaction. However, the origin of the giant dielectric constant remains controversial due to the complexity of the interface and the lack of effective tools to reveal defects and boundary effects. In this work, CaCu3Ti4O12 ceramics with different oxygen concentrations were prepared and the influence of defects on their electrical properties was studied by cyclic voltammetry method. It was found that the resistance of CaCu3Ti4O12 decreases with increasing the number of cyclic voltammetry conditioning and after certain cycles, the voltampere (CV) characteristics change dramatically from nonlinear to linear. In addition, the resistance transition is strongly dependent on the oxygen concentration, and samples sintered in a vacuum with more oxygen vacancies are more easily induced. A filamentary mechanism of oxidation-reduction reaction was proposed to explain the resistive transition of CaCu3Ti4O12.