However, many of these factors are

然而，这些因素中的许多可能相互关联，这使得很难分离它们的单独效应或与内在尺寸效应分开。因此，<br>人们开发了各种模型来解释尺寸效应，92,93 尽管没有就公认模型达成一致意见。唯一被广泛接受的观点是，尺寸效应不仅源于<br>内在原子级极化，但也由材料的外在性质决定，这与加工历史和 NC 的结晶度密切相关。 46 由于这些模型中的大多数在其他文献中都有广泛的回顾，因此我们在这里主要关注最新和流行的模型，“核-壳”模型，目的是提供关于复杂铁电相变和介电特性的清晰说明，这些特性将在材料合成（第 3 节）和单晶表征中介绍（第 4 节）部分。该模型由各种结构表征技术证明，最初由 Tsurumi 等人提出，75,76 并发现与实验观察到的介电特性非常匹配。

However, many of these factors are likely interrelated with each other, which make it difficult to isolate their individual effects or separate with the intrinsic size effect. As a result, variousmodels have been developed to explain the size effect,92,93 though no agreement on accepted models exists. The only widely accepted point is that the size effect not only originates from theintrinsic atomic-scale polarization, but is also determined by the extrinsic nature of the material which is strongly related to processing history and the crystallinity of the NCs.46 As most of these models are reviewed extensively in other literature, here we focus primarily on the most recent and popular model,the ‘‘core–shell’’ model, with the goal of providing a clear illustration on the complex ferroelectric phase transition and dielectric properties which will be covered in the Materials synthesis(Section 3) and Single-crystal characterization (Section 4) parts.This model, evidenced by various structure characterization techniques, was initially proposed by Tsurumi et al.,75,76 and is found to match well to the experimentally observed dielectric properties.<br>

然而，这些因素中有许多可能是相互关联的，这使得很难分离它们各自的影响或与内在的尺寸效应分开。因此，各种已经开发了模型来解释尺寸效应，92，93尽管还没有公认的模型。唯一被广泛接受的观点是，尺寸效应不仅源于本征原子级极化，但也由材料的非本征性质决定，这与加工历史和NCs的结晶度密切相关。46由于大多数这些模型在其他文献中有广泛的回顾，这里我们主要关注最近和流行的模型，即“核-壳”模型，目的是提供复杂铁电相变和介电特性的清晰说明，这将在材料合成(第3节)和单晶表征(第4节)部分中涵盖。该模型由各种结构表征技术证明，最初由Tsurumi等人在75，76中提出，并被发现与实验观察到的介电特性非常匹配。