Specific features of the dielectric spectrum of CaCu3Ti4O12 in the low-frequency range

The dielectric spectra of CaCu3Ti4O12 ceramics with giant values of the dielectric constant have been presented. The spectrum exhibits Debye dispersion with an activation energy of 0.075 eV in the high-frequency range of 106–107 Hz, and a characteristic plateau has been seen in the frequency dependence of the dielectric constant in the range of 104–105 Hz. A considerable increase in the loss factor ɛ″ has been observed in the low-frequency part of the spectrum and a capacitive-to-inductive impedance transition has been revealed in some samples at a frequency below 10−2 Hz. The causes of this transition have been discussed.