Electrical modeling of a CaCu3Ti4O12 ceramic for capacitor applications

Abstract

CaCu3Ti4O2 (CCT) is a material of high interest since colossal permittivity (epsiv>105) has been evidenced in these ceramics. Such properties make it a good candidate for capacitor applications. Electrical characterizations have been carried out on samples of CCT, namely impedance spectroscopy and conduction current measurements. A previous work concerning the modeling of this material showed good agreement with the measurements performed on samples at room temperature and in 102-15.106Hz frequency range. In this paper, new results are presented. On one hand, different materials ranging from pure CCT to multiphase materials presenting different geometries have been manufactured. On the other hand, further impedance spectroscopy measurements have been carried out thanks to a Novocontrol impedance spectroscopy set in a wide range of temperature and frequencies, respectively 120 to 470 K and 10-1-107 Hz. Polarization current measurements thanks to a Keithley 6517A electrometer were directed in parallel. The preliminary study in frequency domain from small signal measurements coupled with static conduction current measurements lead us to implement an electrical model well fitted for simulations in time domain. This frequency model is converted into a time domain model (state space representation) using the diffusive representation tool. In this paper, this approach is extended taking into account temperature influence.