Study on Bi2O3 doping methods and dielectric property of (1 − x)BaTiO3-x(Bi0.5Na0.5)TiO3 ceramics

Extensive studies on Bi2O3 doping methods and contents of (1 − x)BaTiO3-x(Bi0.5Na0.5)TiO3 ((1 − x)BT-xBNT, x = 0.01, 0.03, 0.05, 0.10, 0.15, 0.25 mol) ceramics have been investigated. The samples were fabricated by the conventional ceramic process, while Bi2O3, Na2CO3, and TiO2 were doped in the molar ratio of 1:1:4 and 1.005:1:4 (Bi-excess), respectively, to create (Bi0.5Na0.5)TiO3. The temperature dependence dielectric constant and loss revealed that (1 − x)BT-xBNT ceramics had a typical relaxor behavior and diffuse phase transition characteristics and the degree of ferroelectric relaxation behavior was enhanced with the increase of BNT-dopant concentration. In addition, all the tan δ-T curves showed a low and broad platform under 100 °C. The room temperature permittivity decreased sharply at x ≤ 0.05 mol and then they varied slowly with x increasing. The temperature of permittivity maximum (Tm) could be improved when x ≤ 0.15 mol and this tendency was more apparent when doped with excess Bi2O3.