Effects of Co–Doping on Dielectric and Electrical Responses of CaCu3Ti4-x(Nb1/2In1/2)xO12 Ceramics

Abstract

In this work, CaCu3Ti4-x(Nb1/2In1/2)xO12 ceramics, x = 0, 0.025, 0.05, 0.10, and 0.20, were prepared using a conventional solid state reaction method. Their crystal structure, microstructure, dielectric, and electrical properties were systematically investigated. A primary phase of CaCu3Ti4O12 ceramic was clearly observed in all samples. The average grain size of CaCu3Ti4O12 was decreased by (Nb5+, In3+) doping. The dielectric permittivity of CaCu3Ti4-x(Nb1/2In1/2)xO12 ceramics was slightly dependent on frequency as the co-dopant concentration increased, which was due to a decrease in its grain size. Their dielectric behavior can be well described by the internal barrier layer capacitor (IBLC) model based on interfacial polarization at grain boundaries. The grain boundary resistance and potential barrier height at the grain boundary of CaCu3Ti4O12 were reduced by co–doping with (Nb5+, In3+) ions, resulting in an enhancement of DC conductivity and the related dielectric loss tangent.