Finding the fivefold path Crystals formed in nature or synthesized in a lab can have domains with different orientations that are called twins. Having five of these domains is relatively common, but how these fivefold twins form is still a mystery. Song et al. combined in situ transmission electron microscope observations with simulations to find two different pathways for forming fivefold twins in gold, platinum, and palladium nanoparticles. This combination provides a key insight into the twin-forming process, which might be exploited for developing nanoparticles suitable for a variety of applications. Science, this issue p. 40 Step-by-step mechanisms for forming fivefold twinned nanoparticles are demonstrated in gold, platinum, and palladium. Natural and synthetic nanoparticles composed of fivefold twinned crystal domains have distinct properties. The formation mechanism of these fivefold twinned nanoparticles is poorly understood. We used in situ high-resolution transmission electron microscopy combined with molecular dynamics simulations to demonstrate that fivefold twinning occurs through repeated oriented attachment of ~3-nanometer gold, platinum, and palladium nanoparticles. We discovered two different mechanisms for forming fivefold twinned nanoparticles that are driven by the accumulation and elimination of strain. This was accompanied by decomposition of grain boundaries and the formation of a special class of twins with a net strain of zero. These observations allowed us to develop a quantitative picture of the twinning process. The mechanisms provide guidance for controlling twin structures and morphologies across a wide range of materials.

中文翻译：

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定向附着通过形成和分解高能晶界诱导五重孪晶

寻找五重路径 在自然界形成或在实验室合成的晶体可以具有不同方向的域，称为孪晶。拥有五个这样的领域相对常见，但这些五重双胞胎如何形成仍然是个谜。宋等人。将原位透射电子显微镜观察与模拟相结合，找到了在金、铂和钯纳米粒子中形成五重孪晶的两种不同途径。这种组合提供了对孪生形成过程的关键见解，可用于开发适用于各种应用的纳米粒子。科学，这个问题 p。40 在金、铂和钯中演示了形成五重孪晶纳米粒子的逐步机制。由五重孪晶晶畴组成的天然和合成纳米粒子具有不同的特性。这些五重孪晶纳米粒子的形成机制知之甚少。我们使用原位高分辨率透射电子显微镜结合分子动力学模拟来证明五重孪晶是通过约 3 纳米金、铂和钯纳米颗粒的重复定向附着而发生的。我们发现了两种不同的形成五重孪晶纳米粒子的机制，它们是由应变的积累和消除驱动的。这伴随着晶界的分解和净应变为零的特殊孪晶类的形成。这些观察使我们能够对孪生过程进行定量分析。