Structure map for embedded binary alloy nanocrystals

Yuan, Chris; Shin, S. J.; Liao, Chang; Guzman, J.; Stone, Peter; Watanabe, Masashi; Ager, Joel W.; Häller, E. E.; Chrzan, D. C.

doi:10.1063/1.3027066

Cited by 16 publications

(18 citation statements)

References 11 publications

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“…Inspired by a simple thermodynamic model, we aimed at calculating the specific shape of a Cu–Ag crescent and the energy difference between various geometries. While the model described in ref is general, we apply this model to our specific Cu–Ag system.…”

Section: Results and Discussionmentioning

confidence: 99%

“…As such, we decided to investigate whether the formation of bimetallic NCs of Cu and Ag can be predicted with a simple thermodynamic model focused on surface and interface effects. We have revisited models studying wetting in multiphase systems − to probe how the geometry of Cu and Ag domains in a nanoparticle is primarily determined by the ratio of surface and interface energies. Here, surface energy refers to the energy needed to create a boundary between a solid and a vapor, while interface energy is the cost to create an interface between two different solids .…”

Section: Introductionmentioning

confidence: 99%

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Tailoring Morphology of Cu–Ag Nanocrescents and Core–Shell Nanocrystals Guided by a Thermodynamic Model

Osowiecki

Satish

et al. 2018

J. Am. Chem. Soc.

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The ability to predict and control the formation of bimetallic heterogeneous nanocrystals is desirable for many applications in plasmonics and catalysis. Here, we report the synthesis and characterization of stable, monodisperse, and solution-processed Cu-Ag bimetallic nanoparticles with specific but unusual elemental arrangements that are consistent with a recently developed thermodynamic model. Using air-free scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy, the distribution of Cu and Ag positions was unambiguously identified within individual nanocrystals (NCs), leading to the discovery of a Cu-Ag nanocrescent shape. A simple yet versatile thermodynamic model was applied to illustrate how the interplay between surface and interface energies determines the particle morphology. It is found that there exists a range of surface-to-interface energy ratios under which crescent-shaped nanocrystals are the thermodynamically favored products, with the morphology tunable by adjusting the Ag content. We further show the conversion of Cu-Ag nanocrescents into Ag@CuO upon mild oxidation, whereas fully core-shell Cu@Ag NCs are robust against oxidation up to 100 °C. The plasmonic and interband absorptions of Cu-Ag NCs depend on the composition and the degree of Cu oxidation, which may find application in light-driven catalysis.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tailoring Morphology of Cu–Ag Nanocrescents and Core–Shell Nanocrystals Guided by a Thermodynamic Model

Osowiecki

Satish

et al. 2018

J. Am. Chem. Soc.

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“…From that we calculated the value of 1 and 2 using the relation shown in the text ((Equation 1and 2)). The notations are per the reference [38].…”

Section: Resultsmentioning

confidence: 99%

“…To check whether the bi-lobed structures are equilibrium structures or not, we calculated the 1 and 2 values for the bi-lobed structures and applied the formulas used by the Yuan et al [38] in their calculation. The value of the 1 (= 1.05) and 2 (= 1.07) were well matched with the studied done by Yuan et al [38]. So these Au-Ge bilobed structures are most likely the equilibrium structures.…”

Section: Resultsmentioning

confidence: 99%

Nano scale phase separation in Au-Ge system on ultra clean Si(100) surfaces

Rath

Dash

Juluri

et al. 2012

Journal of Applied Physics

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We report on the formation of lobe-lobe (bi-lobed) Au-Ge nanostructures under ultra high vacuum (UHV) conditions (≈3× 10 -10 mbar) on clean Si(100) surfaces. For this study, ≈2.0 nm thick Au samples were grown on the substrate surface by molecular beam epitaxy (MBE). Thermal annealing was carried out inside the UHV chamber at temperature ≈500°C and following this, nearly squareshaped Au x Si 1-x nano structures of average length ≈ 48 nm were formed. A ≈2 nm Ge film was further deposited on the above surface while the substrate was kept at a temperature of ≈500°C.Well ordered Au-Ge nanostructures where Au and Ge residing side by side (lobe-lobe structures) were formed. In our systematic studies, we show that, gold-silicide nanoalloy formation at the substrate (Si) surface is necessary for forming phase separated Au-Ge bilobed nanostructures.Electron microscopy (TEM, STEM-EDS, SEM) studies were carried out to determine the structure of Au -Ge nano systems. Rutherford backscattering Spectrometry measurements show gold interdiffusion into substrate while it is absent for Ge.. PACS: 81.15. Hi, 64.75.St, 81.15.Aa

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“…Here, a method for determining interfacial free energies within BEANs is proposed. Specifically, the equilibrium geometry of a BEAN is determined by the relevant interfacial free energies, 12 and characterization of this geometry enables one to deduce ratios of the relevant interfacial free energies. These ratios, when combined with experimental results for bulk alloys, provide a measure of interfacial free energy.…”

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confidence: 99%