Ferroelectric properties of bismuth layer-structured oxides

Abstract

Basic ferroelectric properties of SrBi₂Ta₂O₉ (SBT) ceramics are mainly studied on the effects of the ratio of Sr/Bi/Ta and grain orientation on dielectric constant ϵs, loss tangent tan δ, Curie temperature, T_c , and D—E hysteresis loops, that is, the remanent polarization, Prand the coercive field, E_c . The maximum value of the ϵ _s MAX (=849), P_r (=∼7 μC/cm²) and the minimum value of the T_c (=435°C) was obtained for the stoichiometry (Sr/Bi/Ta = 1/2/2) composition. The value of ϵ _s MAX (=890) of the grain orientation direction perpendicular to the forging axis has been enhanced than that of non-oriented ceramics.

Key Words:

• Bismuth layer-structured ferroelectrics
• SrBi₂Ta₂O₉ ceramics
• D–E hysteresis loop
• grain orientation
• hot-forging