Effect of semiconductive grain and microstructure on the dielectric properties of CaCu3Ti4O12 ceramics with Sr2+ doping

Abstract

Abstract Compositions based on Ca1−xSrxCu3Ti4O12(x = 0, 0.05, 0.1, 0.2) were prepared via the conventional solid state synthesis methods, influence of semiconductive grain and microstructure on the dielectric properties of CaCu3Ti4O12 ceramics was studied. UV–vis absorption spectra and photoluminescence measurement indicated that the semiconductive of grains changed with Sr2+ doping, and the band gap of materials increased from 2.25 eV to 2.30 eV. According to the model Schottky-type barrier formed between the grain boundaries (GBs), we analyzed that increased band gap would lead to increase of the potential barrier of height, thus grain boundary resistance increased and the dielectric constants decreased. However, microstructure of Ca1−xSrxCu3Ti4O12 contributed to the dielectric properties were researched, the grain size became larger with Sr2+ doping, thus the dielectric constants increased and grain boundary resistance decreased with Sr2+ doping. The results showed that Schottky-type barriers between GBs were the factors to form the special dielectric properties of CCTO, and microstructure would influence the dielectric properties notably.