About this Abstract |
| Meeting |
2027 TMS Annual Meeting & Exhibition
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| Symposium
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Four-Dimensional Scanning Transmission Electron Microscopy (4D STEM) for Quantitative Materials Characterization
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| Presentation Title |
4D-STEM diffraction tomography of lattice mismatched nanoparticles |
| Author(s) |
Qian Chen |
| On-Site Speaker (Planned) |
Qian Chen |
| Abstract Scope |
Strain at heterogeneous interfaces enables materials properties including band-structure shifts in thin-film semiconductors, precipitation strengthening in steels, and enhanced catalysis in nanoparticles. Yet high-resolution three-dimensional strain mapping remains challenging because interfacial relaxation depends on composition and geometry. In this talk, I will introduce dual-space nanoscopic strain tomography with 2-nm resolution using four-dimensional scanning transmission electron microscopy (4D-STEM). Applied to nanoparticles with well-defined three-dimensional interfaces and lattice mismatches up to 11%, the method reveals partial or complete strain relaxation within a few nanometers of the interface. It also resolves highly strained nanoscale domains near defects and locates them in three dimensions, features obscured in two-dimensional maps. We identify a hierarchy of relaxation mechanisms: surface relaxation in single-component nanoparticles, stacking faults and dislocations at intermediate mismatch, and dislocation aggregation into low-angle boundaries at high mismatch. This approach complements X-ray methods and digital volume correlation while enabling studies of deformation and strengthening. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Characterization, Nanotechnology, Mechanical Properties |