Microstructure and dielectrical properties of CaCu3Ti4O12/TiO2 composite ceramics with core-shell structure

The large low-frequency dielectric loss of CaCu3Ti4O12 (CCTO) ceramics limit their applications. According to the internal barrier layer capacitance effect, which is the most widely accepted explanation for the giant-epsilon' phenomenon of CCTO ceramics, increasing the resistance of grain boundary is an effective way to reduce their low-frequency dielectric loss. In this work, CCTO/TiO2 composite ceramics with coreshell structure were prepared by sol-gel-like method, and their crystalline structures, microstructures, dielectrical properties and complex impedance were investigated systematically. The results show that the room temperature low-frequency dielectric loss of our CCTO-based ceramics decreased significantly by TiO2-doping and annealing in oxygen, which should be attributed to the increasing resistance of the insulating grain boundary. (C) 2018 Elsevier B.V. All rights reserved.