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Stress effect on segregation and ordering in Pt–Ag nanoalloys
Journal of Physics: Condensed Matter ( IF 2.3 ) Pub Date : 2021-03-08 , DOI: 10.1088/1361-648x/abe07a
Alexis Front 1 , Christine Mottet 1
Affiliation  

We performed a theoretical study of the chemical ordering and surface segregation of Pt–Ag nanoalloys in the range of size from 976 to 9879 atoms (3.12 to 6.76nm). We used an original many-body potential able to stabilize the L11 ordered phase at equiconcentration leading to a strong silver surface segregation. Based on a recent experimental study where nanoparticles up to 2.5nm have been characterized by high transmission electron microscopy with the L11 ordered phase in the core and a silver surface shell, we predict in our model via Monte Carlo simulations that the lower energy configuration is more complicated with a three-shell alternance of Ag/Pt/Ag from the surface surrounding the L11 ordered phase in the core. The stress analysis demonstrates that this structure softens the local stress distribution inside the nanoparticle which contributes to reduce the internal energy.



中文翻译:

应力对 Pt-Ag 纳米合金偏析和有序的影响

我们对 976 至 9879 个原子(3.12 至 6.76nm)尺寸范围内的 Pt-Ag 纳米合金的化学排序和表面偏析进行了理论研究。我们使用了一个原始的多体势能,能够在等浓度下稳定 L1 1有序相,从而导致强烈的银表面偏析。基于最近的一项实验研究,其中高达 2.5nm 的纳米粒子已通过高透射电子显微镜进行表征,其中核中的 L1 1有序相和银表面壳,我们通过蒙特卡罗模拟在我们的模型中预测,较低的能量配置是更复杂的是从 L1 1周围的表面的 Ag/Pt/Ag 的三壳交替核心中的有序相。应力分析表明,这种结构软化了纳米粒子内部的局部应力分布,有助于降低内能。

更新日期:2021-03-08
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