Abstract
The structure of monometallic decahedral multiply twinned nanoparticles (MTPs) has been extensively studied, whereas less is known about intermetallic MTPs, especially the mechanism of formation of multiply twinned structures, which remains to be understood. Here, by using aberration-corrected scanning transmission electron microscopy, a detailed structural study of AuCu decahedral intermetallic MTPs is presented. Surface segregation has been revealed on the atomic level and the multiply twinned structure was studied systematically. Significantly different from Au and Cu, the intermetallic AuCu MTP adopts a solid-angle deficiency of -13.35°, which represents an overlap instead of a gap (+7.35° gap for Au and Cu). By analysing and summarizing the differences and similarities among AuCu and other existing monometallic/intermetallic MTPs, the formation mechanism has been investigated from both energetic and geometric perspectives. Finally, a general framework for decahedral MTPs has been proposed and unknown MTPs could be predicted on this basis.
Highlights
Nanoparticles (NPs) have received considerable attention for a variety of applications in the fields of energy (Liu et al, 2015), catalysis (Luo & Guo, 2017), environment (Nel et al, 2009) and biology (Gao et al, 2004)
In the present work, using aberration-corrected scanning transmission electron microscopy (AC-STEM), we provide a detailed structural analysis of intermetallic AuCu multiply twinned particles (MTPs)
We have demonstrated an in-depth atomic scale structural study of AuCu intermetallic decahedral MTPs
Summary
Nanoparticles (NPs) have received considerable attention for a variety of applications in the fields of energy (Liu et al, 2015), catalysis (Luo & Guo, 2017), environment (Nel et al, 2009) and biology (Gao et al, 2004). Multi-elemental NPs have received great attention because of the wide tunability of their structures and properties leading to applications such as electrocatalysis (Zhang et al, 2014; Kim et al, 2014; Feng et al, 2018; Zhan et al, 2017; Prabhudev et al, 2013). Owing to their structural diversity, understanding the microstructure of multielemental NPs is crucial for materials design and interpretation of performance. The contrast of the high-angle annular dark-field STEM (HAADF-STEM) image arises from the scattering electrons,
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