Dielectric properties of CaCu3Ti4O12 (CCTO) doped with GeO2

The CaCu3Ti4O12 (CCTO) is a compound with an extraordinarily high dielectric constant at room temperature (104–105), and almost invariable from 100 to 600 K. Some researchers suggested that this dielectric behaviour is intrinsic, while others attributed this behaviour to extrinsic effects. Among the last ones, the barrier layer capacitor model (BLC) is commonly accepted. The preparation method and doping has a great influence on the microstructure and dielectric properties of this material. In this work, CCTO was prepared by solid state conventional technique, using CuO, TiO2, CaCO3 as starting materials. The prepared material was mixed with concentrations up to 14% of GeO2 by weight, and sintered at 1050 °C, during 12 h. The samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and dielectric measurements in the 100 Hz–30 MHz frequency range, at room temperature. The effects of GeO2 concentration on the segregation phase are studied and correlated with the relaxation parameters calculated using the Cole–Cole model of dielectric relaxation.