In this work, the dependency of the polarization (P) - electric field (E) loop area $A$ of lead free ferroelectrics Na_0.5Bi_0.5TiO₃ (NBT), K_0.5Bi_0.5TiO₃ (KBT), and Na_0.25K_0.25Bi_0.5TiO₃ (NKBT) on the amplitude ($E_0$) of the electric field is studied. Based on the nature of the hysteresis loop with increasing $E_0$, the $lnA$ versus $ln{E}_0$ graph is divided into three stages and the scaling exponents of each stage are estimated. In the third stage, NBT, KBT, and NKBT show different shapes of P-E loops (square, slanted and pinched, respectively). Although, almost similar slopes in the third stage are obtained from the $lnA$ versus $ln{E}_0$ graphs of KBT and NKBT, the formation of pinched P-E loop of NKBT is discussed based on the current-time curve under a complete cycle of the applied electric field. The shape of the P-E loop also affects the recoverable energy storage density $(W_{rec}$) of the material. Similar to the scaling of $A$, the variation of $ln{W}_{rec}$ with $ln{E}_0$ of NBT, KBT and NKBT are examined. Interestingly, three stages are only noticed in the $ln{W}_{rec}-$ $ln{E}_0$ curve of pinched P-E loop (NKBT), whereas $ln{W}_{rec}$ linearly increases with $ln{E}_0$ for square and slanted P-E loop. Such type of behavior of $W_{rec}$ of NKBT is explained based on the reversible domain switching mechanism of the pinched P-E loop.

在这项工作中，极化 (P) - 电场 (E) 环路面积的依赖性$\mathrm{一个}$在振幅_{( _} _ _{_} _ _ _{_} _ _{_} _ _{_} _ _{_} _ _{_} _ _{_} _ _{_}${乙}_0$) 的电场进行了研究。基于磁滞回线的性质，随着增加${乙}_0$， 这$ln\mathrm{一个}$相对$ln{乙}_0$图分为三个阶段，并估计每个阶段的缩放指数。在第三阶段，NBT、KBT 和 NKBT 显示出不同形状的 PE 环（分别为方形、倾斜和捏合）。虽然，第三阶段几乎相似的斜率是从$ln\mathrm{一个}$相对$ln{乙}_0$在KBT和NKBT的曲线图上，根据施加电场的一个完整周期下的电流-时间曲线，讨论了NKBT的收缩PE环的形成。PE回路的形状也会影响可恢复的储能密度$(W_{reC}$) 的材料。类似于缩放$\mathrm{一个}$, 的变化$ln{W}_{reC}$和$ln{乙}_0$对 NBT、KBT 和 NKBT 进行检查。有趣的是，三个阶段只在$ln{W}_{reC}-$ $ln{乙}_0$收缩 PE 环 (NKBT) 的曲线，而$ln{W}_{reC}$随着线性增加$ln{乙}_0$用于方形和倾斜 PE 环。这种类型的行为$W_{reC}$NKBT 的解释基于收缩 PE 环路的可逆域切换机制。