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首页> 外文期刊>Physical review >Phase stability, ordering tendencies, and magnetism in single-phase fee Au-Fe nanoalloys
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Phase stability, ordering tendencies, and magnetism in single-phase fee Au-Fe nanoalloys

机译：单相费金铁纳米合金的相稳定性，有序性和磁性

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摘要

Bulk Au-Fe alloys separate into Au-based fee and Fe-based bee phases, but L1_0 and L1_2 orderings were reported in single-phase Au-Fe nanoparticles. Motivated by these observations, we study the structural and ordering energetics in this alloy by combining density functional theory (DFT) calculations with effective Hamiltonian techniques: a cluster expansion with structural filters, and the configuration-dependent lattice deformation model. The phase separation tendency in Au-Fe persists even if the fcc-bcc decomposition is suppressed. The relative stability of disordered bee and fee phases observed in nanoparticles is reproduced, but the fully ordered L1_0 AuFe, L1_2 Au_3Fe, and L1_2 AuFe_3 structures are unstable in DFT. However, a tendency to form concentration waves at the corresponding [001] ordering vector is revealed in nearly random alloys in a certain range of concentrations. This incipient ordering requires enrichment by Fe relative to the equiatomic composition, which may occur in the core of a nanoparticle due to the segregation of Au to the surface. Effects of magnetism on the chemical ordering are also discussed.
机译：块状的Au-Fe合金分为Au基的Fe相和Fe基的蜂相，但是在单相Au-Fe纳米颗粒中报告了L1_0和L1_2有序。基于这些观察结果，我们通过结合密度泛函理论（DFT）计算与有效的汉密尔顿技术（包括结构滤波器的簇扩展以及与构型有关的晶格变形模型），研究了该合金的结构和有序能级。即使抑制了fcc-bcc分解，Au-Fe中的相分离趋势也持续存在。再现了在纳米粒子中观察到的无序蜂和电荷相的相对稳定性，但是在DFT中，完全有序的L1_0 AuFe，L1_2 Au_3Fe和L1_2 AuFe_3结构不稳定。然而，在一定浓度范围内的几乎随机合金中，揭示出在相应的[001]有序向量处形成浓度波的趋势。这种初期有序化要求Fe相对于等原子组成富集，这可能由于Au在表面的偏析而出现在纳米颗粒的核中。还讨论了磁性对化学有序性的影响。

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  • 来源
    《Physical review》 |2017年第13期|134109.1-134109.21|共21页
  • 作者

    I. A. Zhuravlev; S. V. Barabash; J. M. An; K. D. Belashchenko;

  • 作者单位

    Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln,Lincoln, Nebraska 68588, USA;

    Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln,Lincoln, Nebraska 68588, USA,Intermoleular Inc., San Jose, California 95134, USA;

    Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln,Lincoln, Nebraska 68588, USA;

    Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln,Lincoln, Nebraska 68588, USA;

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