Capturing Nucleation at 4D Atomic Resolution

ORAL

Abstract

Nucleation is a ubiquitous phenomenon in many physical and biological processes. However, it is a challenging process to study nucleation due to the lack of experimental tools to directly measure the 3D atomic structure of nuclei. Here, we further advance atomic electron tomography to study the early stage nucleation of FePt nanoparticle system at 4D atomic resolution [1]. We reveal that early stage nuclei are irregularly shaped, each has a core of a maximum order parameter, and an order parameter gradient points from the core to the boundary of the nucleus. We also capture the 3D atomic structure and dynamics of the same nuclei undergoing growth, fluctuation, dissolution, merging and/or division. We find that nucleation dynamics is regulated by the distribution of the order parameter and its gradient. These experimental results differ from classical nucleation theory (CNT), and we propose an order parameter gradient nucleation model which is thermodynamically more favorable than CNT. We further corroborate this model using molecular dynamics simulations of the liquid-solid phase transition of Pt.
[1] J. Zhou et al., arXiv:1807.10709 (2018).

*STROBE: NSF STC (DMR-1548924), US DOE (DE-SC0010378), the NSF DMREF (DMR-1437263), and the Molecular Foundry (US DOE DE-AC02-05CH11231)

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Presenters

  • Yongsoo Yang

    • Physics and Astronomy, University of California, Los Angeles

Authors

  • Yongsoo Yang

    • Physics and Astronomy, University of California, Los Angeles

  • Jihan Zhou

    • Physics and Astronomy, University of California, Los Angeles

  • Yao Yang

    • Physics and Astronomy, University of California, Los Angeles

  • Dennis S Kim

    • Physics and Astronomy, University of California, Los Angeles

  • Andrew Yuan

    • Physics and Astronomy, University of California, Los Angeles

  • Xuezeng Tian

    • Physics and Astronomy, University of California, Los Angeles

  • Colin Ophus

    • Molecular Foundry, Lawrence Berkeley National Laboratory
    • Lawrence Berkeley National Laboratory

  • Fan Sun

    • Physics, University at Buffalo

  • Andreas Schmid

    • Molecular Foundry, Lawrence Berkeley National Laboratory

  • Michael Nathanson

    • Chemical and Biological Engineering, University of Colorado, Boulder

  • Hendrik Heinz

    • Chemical and Biological Engineering, University of Colorado, Boulder

  • Qi An

    • Chemical and Materials Engineering, University of Nevada, Reno

  • Hao Zeng

    • Physics, University at Buffalo
    • Physics, University at Buffalo, State University of New York

  • Peter Ercius

    • Molecular Foundry, Lawrence Berkeley National Laboratory
    • Lawrence Berkeley National Laboratory

  • Jianwei Miao

    • Physics and Astronomy, University of California, Los Angeles