Dielectric Properties in CaCu3Ti4O12 Single Crystal at High Temperatures.

High-temperature dielectric properties of perovskite-related CaCu3Ti4O12 single and polycrystalline samples were studied. Both samples show a very similar high dielectric response, while the value of single crystal is about two times as large as those of polycrystalline ceramic samples. The dielectric constant shows a shoulder-like round anomaly around 600 K with increasing temperature, and a dielectric anomaly at 726 K for the present single crystal (732 K for ceramic samples). The present evidence means that a structural phase transition occurs in CaCu3Ti4O12 at 726 K. The origin of high dielectric response is not related to an extrinsic one due to grains and grain boundary layers. [ABSTRACT FROM AUTHOR]