Effect of doping ions on the structural defect and the electrical behavior of CaCu3Ti4O12 ceramics

•Y and Ta doping cause different defect types and concentration.•Defect influences the grain boundary mobility and results in different grain size.•Y doping increases the dielectric constant and decreases the nonlinear property.•Ta doping decreases the dielectric constant and enhances the nonlinear property.•Zr doped sample has nearly the defect type and dielectric properties as CaCu3Ti4O12.

The microstructure, dielectric and electrical properties of CaCu3Ti4−xRxO12 (R = Y, Zr, Ta; x = 0 and 0.005) ceramics were investigated by XRD, Raman spectra, SEM and dielectric spectrum measurements. Positron annihilation measurements have been performed to investigate the influence of doping on the defects. The results show that all samples form a single crystalline phase. Y and Ta doping cause different defect types and increase the defect size and concentration, which influence the mobility of grain boundary and result in the different grain size. Y doping increases the dielectric constant and decreases the nonlinear property while Ta doping lead to an inverse result. Zr-doped sample has nearly the defect type, grain morphology and dielectric properties as pure CaCu3Ti4O12. The effects of microstructure including the grain morphology and the vacancy defects on the mechanism of the dielectric and electric properties by doping are discussed.

Graphical abstractThe dielectric constant decreases with Ta doping, increases with Y doping and keeps almost constant with Zr doping compared with that of pure CCTO.Figure optionsDownload full-size imageDownload as PowerPoint slide