Although extensive studies have been done on lead-free dielectric ceramics to achieve excellent dielectric behaviors and good energy storage performance, the major problem of low energy density has not been solved so far. Here, we report on designing the crossover relaxor ferroelectrics (CRFE), a crossover region between the normal ferroelectrics and relaxor ferroelectrics, as a solution to overcome the low energy density. CRFE exhibits smaller free energy and lower defect density in the modified Landau theory, which helps to obtain ultrahigh energy density and efficiency. The (1–x)Ba_0.65Sr_0.35TiO₃–xBi(Mg_2/3Nb_1/3)O₃ ((1–x)BST–xBMN) (x = 0, 0.08, 0.1, 0.18, 0.2) ceramic was synthesized by a solid-state reaction method. The solid solutions exhibit dielectric frequency dispersion, which suggests typical relaxor characteristics with the increasing BMN content. The crossover ferroelectrics of 0.9BST–0.1BMN ceramic possesses a high energy storage efficiency (η) of 85.71%, a high energy storage density (W) of 3.90 J/cm³, and an ultrahigh recoverable energy storage density (W_rec) of 3.34 J/cm³ under a dielectric breakdown strength of 400 kV/cm and is superior to other lead-free BaTiO₃ (BT)-based energy storage ceramics. It also exhibits strong thermal stability in the temperature range from 25 to 150 °C under an electric field of 300 kV/cm, with the fluctuations below 3% and with the energy storage density and energy efficiency at about 2.8 J/cm³ and 82.93%, respectively. The enhanced recoverable energy density and breakdown strength of BT-based materials with significantly high energy efficiency make it a promising candidate to meet the wide requirements for high power applications.

中文翻译：

---

在无铅BaTiO3基大块陶瓷中实现优异储能性能的有效策略。

尽管已经对无铅介电陶瓷进行了广泛的研究，以实现优异的介电性能和良好的储能性能，但迄今为止，尚未解决低能量密度的主要问题。在这里，我们报告设计跨界弛豫铁电体（CRFE），即在普通铁电体和驰豫铁电体之间的跨接区域，作为克服低能量密度的解决方案。在修正的Landau理论中，CRFE表现出较小的自由能和较低的缺陷密度，这有助于获得超高的能量密度和效率。（1- x）Ba _0.65 Sr _0.35 TiO ₃ - x Bi（Mg _2/3 Nb _1/3）O ₃（（1-x）BST– x BMN）（x = 0，0.08，0.1，0.18，0.2）陶瓷是通过固态反应方法合成的。固溶体表现出介电频率分散，这表明随着BMN含量的增加，典型的弛豫特性。0.9BST–0.1BMN陶瓷的交叉铁电体具有85.71％的高储能效率（η ），3.90 J / cm ³的高储能密度（W）和超高的可回收储能密度（W _rec）在300 kV / cm的介电击穿强度下为3.34 J / cm ³，优于其他无铅BaTiO ₃（BT）基储能陶瓷。在300 kV / cm的电场下，它在25至150°C的温度范围内也表现出很强的热稳定性，波动低于3％，能量存储密度和能量效率分别为2.8 J / cm ³和82.93。 ％， 分别。具有显着高的能源效率的BT基材料增强的可回收能量密度和击穿强度使其成为满足大功率应用广泛需求的有希望的候选者。