Dc-bias-field-induced dielectric relaxation and ac conduction in CaCu3Ti4O12 ceramics

The dielectric relaxation and ac conduction of CaCu3Ti4O12 (CCTO) ceramics were investigated Lit different temperatures under a dc bias. The de bias gives rise to space charge accumulation, i.e. in electrode response, resulting in the significant increase of dielectric permittivity and dielectric loss tangent. Two Debye-like relaxations, arising from electrode and grain boundary responses, are present Lit low frequency with an increase of the dc bias. The electrode and grain boundary relaxations are distinguished according to the impedance spectroscopy and the frequency-dependent ac conductivity. The relaxation times of electrode and grain boundary relaxation are 0.955 ms and 0.026 ms, respectively, with a dc bias of 10 V at 328 K.