Effects of Lu3+ Doping on Microstructures and Electrical Properties of CaCu3Ti4O12 Ceramics

The influences of Lu3+ doping on the structure and electrical properties of CaCu3Ti4O12 (CCTO) ceramics are systematically studied. We find that Lu3+ doping inhibits the grain growth of CCTO while the dielectric constant decreases firstly and then increases with the increase of Lu3+ content. The positron annihilation results indicate defect concentrations increase with the increment of Lu3+ content. At low Lu3+ doped level, the huge dielectric response of the samples mainly derives from the internal barrier layer capacitor (IBLC) effect while intrinsic polarization as defect dipoles makes more contribution at higher doped level. The dielectric loss is depressed due to the increase of cation vacancies and grain boundary resistivity. Good performances (high epsilon(') of similar to 1.1 x 10(4) and low tan delta of similar to 0.025) at 1 kHz are obtained in Ca0.85Lu0.15Cu3Ti4O12 sample. Moreover, the enhanced nonlinear electrical properties are associated with cation vacancy defects generated by Lu3+ doping in the GB region. These findings are helpful in exploring the physical nature of the dielectric properties of CCTO.

Automated summary

The study shows that Lu3+ doping inhibits grain growth of CCTO ceramics, affecting the dielectric constant which decreases first and then increases with Lu3+ content. The presence of Lu3+ increases defect concentrations, leading to different mechanisms contributing to dielectric response at different doping levels. Lu3+ doping also enhances nonlinear electrical properties, associated with cation vacancy defects in the grain boundary region.