Microstructural and Dielectric Properties of SrTiO_3-doped CaCu_3Ti_40_(12) Ceramics

摘要

CaCu_3Ti_40_(12) presents colossal dielectric permittivity within a large temperature and frequency range, which makes it to be a suitable material for technological applications, such as components of capacitive memories and mobile phones. In this investigation, SrTiO_3-doped CaCu_3Ti_40_(12) ceramics were prepared by solid-state reaction. The influence of doping on the structures, compositions and dielectric properties of the materials were investigated by X-ray diffraction, scanning electron microscopy and dielectric measurements between 40 Hz and 110 MHz. The material presents colossal response (ε_r～10~4-10~5) and the dielectric loss tangent decreased with doping level increase at high frequency. The microstructure analysis showed that the second-phase particles segregated in the doped CaCu_3Ti_4O_(12) grain edges. Cole-Cole modeling correlated well the effects of this segregation with the relaxation parameters obtained. The extrinsic contributions for the dielectric response were discussed together with the structural and compositional evolution of SrTiO_3-doped CaCu_3Ti_40_(12) material. The experimental results indicated that SrTiO_3 doping is a suitable method to optimize the dielectric response and electrical properties of CaCu_3Ti_40_(12) for the applications in microelectronic devices.