Effects of Bi3+ doping on microstructure and dielectric properties of CaCu3Ti4O12/CaTiO3 composite ceramics

The effects of Bi3+ doping ions on the microstructure and dielectric properties of CaCu3Ti4O12/CaTiO3 (CCTO/CTO) composites prepared by using a conventional solid state reaction method were investigated. Microstructure analysis revealed that Bi3+ doping ions can be substituted into Ca2+ sites in both the CCTO and CTO phases. It is notable that the value of ε′ at 1 kHz and 30 °C of the CCTO/CTO composite was greatly increased to 4.1×104 by doping with Bi3+ ions, compared to the un-doped sample (ε′~1.8×103). Non-Ohmic properties of Bi3+-doped CCTO/CTO composites were also investigated. The electrical responses of grains and internal interfaces were investigated using impedance spectroscopy. Strongly enhanced dielectric responses and variation in nonlinear electrical properties can be well described based on the electrical responses at internal interfaces of the composites.