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Concentration and strain fields inside a Ag/Au core-shell nanowire studied by coherent X-ray diffraction.
Sabine T Haag1, Marie-Ingrid Richard, Udo Welzel
1Max Planck Institute for Intelligent Systems (formerly Max Planck Institute for Metals Research), D 70569 Stuttgart, Germany. s.haag@is.mpg.de
Nano Letters
|April 23, 2013
Summary
This study reveals that silver/gold core-shell nanowires exhibit decelerated intermixing during annealing, preserving their structure unlike bulk materials. This finding is crucial for understanding nanomaterial stability and diffusion processes.
Area of Science:
- Materials Science
- Nanotechnology
- Solid-State Physics
Background:
- Core-shell nanowires are critical nanostructures with diverse applications.
- Understanding diffusion and intermixing in nanowires is essential for their stability and performance.
- Bulk materials exhibit significant intermixing at elevated temperatures, a behavior not fully understood in nanowires.
Purpose of the Study:
- To investigate the structural behavior of single-crystalline silver/gold (Ag/Au) core-shell nanowires under annealing.
- To determine the extent of intermixing and assess the preservation of core-shell morphology.
- To compare diffusion dynamics in nanowires with those in bulk materials.
Main Methods:
- Recorded three-dimensional coherent diffraction patterns of Ag/Au core-shell nanowires using X-ray diffraction near the Au LIII absorption edge.
- Analyzed two-dimensional slices of the diffraction patterns to study reciprocal space.
- Compared experimental diffraction patterns with simulated patterns to identify coherency strain fields.
Main Results:
- Observed facet streaks and thickness fringes in two-dimensional diffraction patterns, enabling determination of nanowire cross-sectional shape and size.
- Identified a coherency strain field within the nanowire through comparison with simulations.
- Demonstrated that the core-shell morphology was preserved during in situ annealing, indicating significantly decelerated intermixing compared to bulk diffusion.
Conclusions:
- Ag/Au core-shell nanowires maintain their structural integrity under annealing conditions where bulk materials would intermix significantly.
- Intermixing in these nanowires is pronouncedly slower than in bulk Ag/Au.
- The findings highlight unique diffusion properties of nanomaterials and their potential for enhanced stability.
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