Linear dielectric response and dielectric relaxation behavior of bismuth-doped (Ba_(1-x)Ca_(x/2)Sr_(x/2))TiO_3 ceramics

摘要

The structure and electrical properties of bismuth-doped (Ba_(1-x)Ca_(x/2)Sr_(x/2))TiO_3(BCST) (x ≤ 0.40) ceramics prepared using the solid-state reaction were investigated. X-ray diffraction (XRD) analysis shows that 5 at% of Bi doping can be fully incorporated into the perovskite lattice of BCST ceramics. BCST ceramic samples for x < 0.40 have almost the same T_m (T_m is designated as the temperature of the peak dielectric constant, at T_m where the dielectric peak occurs) for different frequencies, while an obvious dielectric relaxation behavior (DRB) is observed in Bi-doped BCST. Bi doping causes T_m to shift to a lower temperature and results in an increase in the degree of diffusion and relaxation of the BCST ceramics. A random electric field is suggested to be responsible for the re-laxor behavior observations. Double-hysteresis loops are observed at lower temperatures in Bi-doped BCST ceramics. The P-E relationship of Bi-doped BCST ceramics shows the dielectric quasilinearity, which indicates that the random local field acts to strongly inhibit the nanodomains.