Dielectric relaxation of BaTiO3 (BTO)-CaCu3Ti4O12 (CCTO) composite screen-printed thick films at low temperatures

In this work, we report electrical measurements of CaCu3Ti4O12 (CCTO) and (BaTiO3-barium titanate, BTO) thick films. The dielectric constant (K) measurements shows that the BTO thick film present a higher K compared to CCTO compound, in the range of frequencies under study. However, for the composite film (CCTO50 and CCTO50T films), one has an unexpected result; the dielectric constant is higher for all the frequencies under study. The BTO-CCTO composite films do not obey the empirical mixing rule. These electric properties were also studied in the temperature range of 80-300 K. For the CCTO film, two relaxation processes were detected. The calculated activation energy was around 0.51 eV for temperatures above 200 K. One second relaxation process was observed on cooling below 200 K with activation energy around 0.061 eV. For the composite film CCTO50T, both relaxation processes are still present. Therefore, these measurements confirm the potential use of such materials for small high dielectric planar devices. These films are also attractive for capacitor applications and certainly for microelectronics, microwave devices (cell mobile phones, for example), where the miniaturization of the devices is crucial. (c) 2005 Elsevier B.V. All rights reserved.