The flexoelectric transition in CaCu3Ti4O12 material with colossal permittivity

Significant flexoelectricity is expected to exist in materials with colossal permittivity. Here, we systematically studied the interplay of flexoelectricity and permittivity in CaCu3Ti4O12 (CCTO) ceramic by examining the thickness and electrode dependence of the flexoelectric coefficients over a wide range of temperatures. We found that an abnormal flexoelectric transition occurs at 95 °C. Below this critical temperature, the barrier layer mechanism dominates the significant flexoelectricity in CCTO ceramic, whereas above this critical temperature, the flexoelectric response mainly originates from the contributions of semiconducting grains and insulating grain boundaries. The observed flexoelectric transition is beneficial not only for developing new materials with high flexoelectric coefficients but also for understanding the colossal permittivity mechanism in CCTO ceramics.