Soria-Sánchez Andrés, Rayas Miguel Angel, Ruiz-Aldana Antonio, de la Rosa-Abad Juan Andrés, Mejía-Rosales Sergio
Dimex Capital, Monterrey 64650, Mexico.
Facultad de Ciencias Físico-Matemáticas, Universidad Autónoma de Nuevo León, San Nicolás de los Garza 66455, Mexico.
Materials (Basel). 2025 Feb 27;18(5):1054. doi: 10.3390/ma18051054.
The thermal stability of bimetallic nanoparticles plays a crucial role in their performance in applications in catalysis, biotechnology, and materials science. In this study, we employ molecular dynamics simulations to investigate the melting behavior of Au-Pd nanoparticles with cuboctahedral, icosahedral, and decahedral geometries. Using a tight-binding potential, we systematically explore the effects of particle size and composition on the melting transition. Our analysis, based on caloric curves, Lindemann coefficients, and orientational order parameters, reveals distinct premelting behaviors influenced by geometry. Larger particles exhibit a coexistence of a pseudo-crystalline core and a partially melted shell, but, in decahedra and icosahedra, melting of the core occurs unevenly, with twin boundaries promoting the melting of one or two of the tetrahedral subunits before the rest of the particle. Notably, icosahedral nanoparticles display higher thermal stability, while both icosahedral and decahedral structures exhibit localized melting within twin boundaries. Additionally, we generate HAADF-STEM simulations to aid the interpretation of in situ electron microscopy experiments.
双金属纳米颗粒的热稳定性在其催化、生物技术和材料科学应用性能中起着关键作用。在本研究中，我们采用分子动力学模拟来研究具有立方八面体、二十面体和十面体几何形状的金 - 钯纳米颗粒的熔化行为。使用紧束缚势，我们系统地探索了颗粒尺寸和组成对熔化转变的影响。我们基于热焓曲线、林德曼系数和取向序参数的分析揭示了受几何形状影响的不同预熔化行为。较大的颗粒表现出伪晶核和部分熔化壳的共存，但在十面体和二十面体中，核的熔化不均匀，孪晶界促进了一个或两个四面体亚基在颗粒其余部分之前的熔化。值得注意的是，二十面体纳米颗粒表现出更高的热稳定性，而二十面体和十面体结构在孪晶界内均表现出局部熔化。此外，我们生成高角度环形暗场扫描透射电子显微镜（HAADF - STEM）模拟以辅助原位电子显微镜实验的解释。
