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

Abstract

The dielectric relaxation and ac conduction of CaCu₃Ti₄O₁₂ (CCTO) ceramics were investigated at different temperatures under a dc bias. The dc bias gives rise to space charge accumulation, i.e. an 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 at 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.

Acknowledgements

This work has been supported by the National Nature Science Foundation (50672075) and the Xi’an S&T Research Foundation (GG05015, GG06023), the SRFDP (20050699011) and EYTP and NCET Program of MOE, Doctorate Foundation (CX200704) and Science Creative Foundation (2006CR06) NPU of China.