arXiv 2102.012202021-02-01cond-mat.mtrl-scicond-mat.mes-hall

界面应变控制下的晶粒形貌预测

Predicting nanocrystal morphology governed by interfacial strain

Hongwei Liu, Xuan Cheng, Nagarajan Valanoor

摘要：

在推广的Wulff-Kaichew（GWK）定理框架下，研究了（001）钛酸锶衬底上具有重要技术意义的氧化镍（NiO）纳米晶的形状依赖性.结果发现，NiO纳米晶体的形状主要取决于界面应变的存在（或不存在）。与衬底具有完全假晶界面（即，外延应变未松弛）的纳米晶体形成具有{001}、{011}、{111}和高折射率{113}暴露小面的嵌入式光滑球冠形态，所述小面具有负伍尔夫点。另一方面，当界面应变被失配位错松弛时，纳米晶体呈现截头棱锥形状，由{111}面和{001}平顶限定，具有正的Wulff点。我们的定量模型能够预测实验观察到的形状和尺寸具有良好的精度。由于异质外延纳米晶体在各种物理化学和电化学功能器件的需求不断增加，这些结果奠定了重要的基础，在利用GWK定理作为一种通用的分析方法来解释异质外延纳米晶体生长的氧化物衬底受界面应变。

英文摘要：

The shape dependence for the technologically important nickel oxide (NiO) nanocrystals on (001) strontium titanate substrates is investigated under the generalized Wulff-Kaichew (GWK) theorem framework. It is found that the shape of the NiO nanocrystals is primarily governed by the existence (or absence) of interfacial strain. Nanocrystals that have a fully pseudomorphic interface with the substrate (i.e. the epitaxial strain is not relaxed) form an embedded smooth ball-crown morphology with {001}, {011}, {111} and high-index {113} exposed facets with a negative Wulff point. On the other hand, when the interfacial strain is relaxed by misfit dislocations, the nanocrystals take on a truncated pyramidal shape, bounded by {111} faces and a {001} flat top, with a positive Wulff point. Our quantitative model is able to predict both experimentally observed shapes and sizes with good accuracy. Given the increasing demand for hetero-epitaxial nanocrystals in various physio-chemical and electro-chemical functional devices, these results lay the important groundwork in exploiting the GWK theorem as a general analytical approach to explain hetero-epitaxial nanocrystal growth on oxide substrates governed by interface strain.

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英文摘要：

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