International audienceDielectric properties of CaCu3Ti4O12 (CCTO)-based ceramics and thick films (e ∼50m) prepared from powders synthesized by a soft chemistry method (co-precipitation) are presented and discussed. The characteristics of pellets and thick films are compared. The pellets exhibit high values of the dielectric permittivity (εr ∼1.4×105) and relatively small dielectric losses (tan δ ∼0.16) at 1 kHz and room temperature. These properties are independent of the nature of the metallization of the electrodes. In addition, the dielectric permittivity decreases when the diameter of the electrodes of the pellets increases, while the losses remain constant. This result, which is strongly related to the nature of the dielectric material in between the electrodes, constitutes a strong indication that the high dielectric permittivity values observed in this material are not related to an interfacial (electrode material) related mechanism but is an internal barrier layer capacitor (IBLC) type. Very high values of the dielectric permittivity of CCTO thick films are measured (εr ∼5×104). The differences in dielectric permittivity between thick films and dense pellets may be attributed to the difference in grain size due to different CuO contents, and to the different reactivity of the materials

CaCu 3 Ti 4 O 12 (CCT) is a material of high interestsince colossal permittivity (ε>10 5 ) 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 10 2 -15.10 6 Hz frequency range [1]. 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 [2][3]. 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 470K and 10 -1 -10 7 Hz. Polarization current measurements thanks to a Keithley 6517A electrometer were directed in parallel. The preliminary study [1] 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.