This study was conducted to understand the nature of the polar state in the morphotropic phase boundary composition 0.67BiFeO₃–0.33BaTiO₃ (0.67BF–0.33BT). Both the unpoled and poled specimens exhibit an average cubic structure. The poling induces a 0.14% increase in the lattice parameter. Macrodomains are absent both in the initial and polar state of 0.67BF–0.33BT. A typical relaxor-type dielectric anomaly was observed (T_f = ~ 627 K, T_B = ~ 820 K). The remnant polarization (P_r), maximum value of electrostrain (S_m), and magnitude strain at E_c in the bipolar mode (S_neg) increase clearly during heating (P_r, ~ 40 µC/cm²; S_m, 0.191% under 40 kV/cm at 453 K). Unlike Bi_0.5Na_0.5TiO₃-based nonergodic relaxors, the first-cycle bipolar electrostrain loops indicate that the minimum strain on the negative side of the bipolar strain curves is negative. Furthermore, the slopes of the relative permittivity versus log frequency plots in unpoled (− 21) and poled (− 23) specimens are similar. The transition between the relaxor state and ferroelectric-like state does not involve a clear dielectric anomaly even in the poled specimen.

进行这项研究是为了了解形态相边界组成0.67BiFeO ₃ –0.33BaTiO ₃（0.67BF–0.33BT）中的极性状态。未极化和极化的样本都显示出平均的立方结构。极化导致晶格参数增加0.14％。在初始状态和极性状态0.67BF–0.33BT中都没有大域。观察到典型的弛豫型电介质异常（Ť _˚F  =〜627 K，Ť_乙 =〜820 K）。在双极模式下，残余极化（P _r），电应变的最大值（S _m）和E _c处的振幅应变（S _neg）在加热期间（P _r，〜40 µC / cm ²；S _m，在453 K下40 kV / cm时为0.191％）明显增加。与基于Bi _0.5 Na _0.5 TiO ₃的非遍历松弛剂不同，第一周期双极电应变环表明双极应变曲线负侧的最小应变为负。此外，在未极化（−21）和极化（−23）样品中，相对介电常数与对数频率图的斜率相似。弛豫态和类铁电态之间的过渡即使在极化试样中也没有明显的介电异常。