The utilization of ferroelectric ceramics in electrical energy storage has become a hot topic due to the urgent need for advanced pulsed power and high power energy storage applications. Much attention has been paid to achieving nanograined ferroelectric ceramics but little to the effect of grain size uniformity, which is critical for dielectric breakdown and reliability. We first investigated this effect via a model based on virtually constructed ceramic samples solved with the phase-field method. Ferroelectric ceramic samples with the same average grain size of typically 100 nm but different uniformity degrees by the variation of the standard deviation values of 83.7, 81.9, 80.1, and 78.7 were constructed via Voronoi tessellation based on a controlled seeding method. The effect of grain size uniformity on the dielectric breakdown was studied through a phase-field dielectric breakdown model. The results indicate that with the standard deviation decreasing, the dielectric breakdown strength is distinctly enhanced. Experimentally, BaTiO3-based ceramics with the same average grain size of 100 nm but different uniformity degrees were realized via conventional sintering and two-step sintering methods. The grain size uniformity of two-step sintered ceramics is greatly improved, which leads to the breakdown strength and discharge energy density of the two-step sintered ceramics about 50% and 100% larger than those of the conventionally sintered ones. This work demonstrates that significant enhancement in dielectric breakdown strength of ferroelectric energy-storage ceramics can be achieved via grain size uniformity control, shedding light on the meticulous design and fine tuning of the energy-storage properties of ferroelectric ceramics.

中文翻译：

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通过晶粒尺寸均匀性控制显着提高铁电储能陶瓷的介电击穿强度：相场模拟和实验实现

由于对先进脉冲电源和大功率储能应用的迫切需求，铁电陶瓷在电能存储中的应用已成为一个热门话题。人们对实现纳米晶粒铁电陶瓷给予了很多关注，但很少关注晶粒尺寸均匀性的影响，这对介电击穿和可靠性至关重要。我们首先通过基于使用相场方法求解的虚拟构造陶瓷样品的模型研究了这种效应。铁电陶瓷样品具有相同的平均晶粒尺寸，通常为 100 nm，但由于标准偏差值的变化为 83.7、81.9、80.1 和 78.7，通过基于受控播种方法的 Voronoi 镶嵌构造了不同的均匀度。通过相场介电击穿模型研究了晶粒尺寸均匀性对介电击穿的影响。结果表明，随着标准偏差的减小，介电击穿强度明显增强。实验上，通过常规烧结和两步烧结方法实现了平均晶粒尺寸相同为 100 nm 但均匀度不同的 BaTiO3 基陶瓷。两步烧结陶瓷的晶粒尺寸均匀性大大提高，使得两步烧结陶瓷的击穿强度和放电能量密度比常规烧结陶瓷大50%和100%左右。