Abstract
Pb-free ceramics of [(0.95-x)(Bi
0.5
Na
0.3
K
0.2
)TiO
3
-0.05(Ba
0.8
Ca
0.2
)TiO
3
doped x(SrTiO
3
) (abbreviation BKNT-ST-BCT) (0.0 ≤ x ≤ 0.2) were prepared by a solid solution technique. The effect of ST (SrTiO
3
) content on the crystal structure and morphology of the sintered ceramics were systemically investigated. Crossover phase transition from ferroelectric to relaxor were observed by increasing ST-content. All virgin samples (x ≤ 0.15) showed a ferroelectric to relaxor diffused phase transition. However, at ST = 0.2, only non-ergodic relaxor (NER) to ergodic relaxor (ER) phase transition was detected. The poled sample of ST = 0.2 showed two phase transitions, denoting domain growth caused by domain wall displacement in a high amplitude electric field. The polarization response was studied under sub-switching cycles of the electric field at different temperatures. The nonlinear behavior showed both ferroelectric and relaxor phases dominated by a Rayleigh-type dynamic. The results suggest that, in the ferroelectric phase, the extrinsic contribution caused by domain wall motion is responsible for majority of dielectric contributions, while in the relaxor phase, the majority of dielectric contribution comes from an intrinsic contribution caused by lattice distortion.