Enhanced dielectric properties of CCTO ceramics doped by different halogen elements

In this work, effects of different halogen elements (F, Br, and I) on the microstructure, morphology, and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics prepared through sol–gel method were systematically studied. It was found that the dielectric loss of the CCTO ceramics doped with F reduced to 0.022 and the breakdown field strength increased to 9.4 kV/cm, simultaneously. Moreover, the Br-doped samples exhibited the lowest dielectric loss of 0.019 and the highest dielectric constant of about 82,047, while the breakdown field strength declined obviously compared to pure CCTO samples. However, in contrast to F or Br element, the I element did not significantly improve the dielectric properties of CCTO ceramics. In addition, the decreased dielectric loss for the doped CCTO ceramics could be owed to the increasing resistance of the grain boundaries, and the improved breakdown field strength could be attributed to the enhanced potential barrier height. All the results suggest that introducing anions, like halogen elements, is an efficient approach to improve the dielectric properties of CCTO ceramics.