Ferroelectric perovskites such as BaTiO₃ and Pb(Zr,Ti)O₃ are well-suited for a variety of applications including piezoelectric transducers and actuators, multilayer ceramic capacitors, thermistors with positive temperature coefficient, ultrasonic and electro-optical devices. Ferroelectricity arises from the long-range ordering of elemental dipoles which determines the appearance of a macroscopic polarization and a spontaneous lattice strain. The confinement of a ferroelectric system in a small volume produces a perturbation of the polar order because of the high fraction of surface atoms and ferroelectricity vanishes when the size of the material is reduced below a critical dimension. This critical size is of a few nanometres in the case of epitaxial thin films and of 10−20 nm for nanoparticles and nanoceramics. The change in properties with decreasing physical dimensions is usually referred to as size effect. Thin films and ceramics are particularly prone to show size effects. A progressive variation of dielectric, elastic and piezoelectric properties of ferroelectric ceramics is already observed when the grain size is reduced below ≈10 μm, i.e. at a length scale much larger than the critical size. In this case it is more appropriate to refer to scaling effects as they are not related to material confinement.

The aim of this contribution is to review the current understanding of size and scaling effects in perovskite ferroelectric ceramics and, in particular, in BaTiO₃. After a short survey on the intrinsic limits of ferroelectricity and on the impact of particle/grain size on phase transitions, the role of interfaces such as ferroelectric/ferroelastic domain walls and grain boundaries in scaling of dielectric and piezoelectric properties will be discussed in detail. Multiple mechanisms combine to produce the observed scaling effects and the maximization of the dielectric constant and piezoelectric properties exhibited by BaTiO₃ ceramics for an intermediate grain size of ≈1 μm. The broad dispersion of experimental data is determined by spurious effects related to synthesis, processing and variation of Ba/Ti ratio. Furthermore, we will consider these size effects, and other properties in relation to the downsizing the modern multilayer BaTiO₃ based capacitors.

铁电钙钛矿，例如BaTiO ₃和Pb（Zr，Ti）O ₃非常适合各种应用，包括压电换能器和致动器，多层陶瓷电容器，具有正温度系数的热敏电阻，超声波和光电器件。铁电源于元素偶极子的远距离排序，它决定了宏观极化和自发晶格应变的出现。将铁电体系限制在小体积内会产生极性顺序的扰动，因为表面原子的比例很高，当材料的尺寸减小到临界尺寸以下时，铁电消失。在外延薄膜的情况下，该临界尺寸为几纳米，对于纳米粒子和纳米陶瓷，该临界尺寸为10-20 nm。物理尺寸减小的特性变化通常称为尺寸效应。薄膜和陶瓷特别容易表现出尺寸效应。当晶粒尺寸减小到≈10μm以下时，即在远大于临界尺寸的长度尺度上，已经观察到铁电陶瓷的介电，弹性和压电性能逐渐变化。在这种情况下，更合适的是引用缩放效果，因为它们与材料限制无关。

该贡献的目的是回顾钙钛矿铁电陶瓷，特别是BaTiO _3中对尺寸和结垢效应的当前理解。在对铁电的固有极限以及颗粒/晶粒尺寸对相变的影响进行了简短调查之后，将详细讨论诸如铁电/铁弹性畴壁和晶界之类的界面在介电和压电性能定标中的作用。多种机制结合在一起产生观察到的缩放效应，并使BaTiO ₃表现出的介电常数和压电性能最大化中等粒度约为≈1μm的陶瓷。实验数据的广泛分散取决于与Ba / Ti比例的合成，加工和变化有关的杂散效应。此外，我们将考虑这些尺寸效应以及与缩小现代多层BaTiO ₃基电容器尺寸有关的其他性能。