Fluctuation cepstral scanning transmission electron microscopy of mixed-phase amorphous materials

Saran Pidaparthy; Haoyang Ni; Hanyu Hou; Daniel P Abraham; Jian-Min Zuo

doi:10.1016/j.ultramic.2023.113718

Fluctuation cepstral scanning transmission electron microscopy of mixed-phase amorphous materials

Ultramicroscopy. 2023 Jun:248:113718. doi: 10.1016/j.ultramic.2023.113718. Epub 2023 Mar 12.

Authors

Saran Pidaparthy¹, Haoyang Ni², Hanyu Hou³, Daniel P Abraham⁴, Jian-Min Zuo⁵

Affiliations

¹ Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, United States.
² Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
³ Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
⁴ Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, United States.
⁵ Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States. Electronic address: jianzuo@illinois.edu.

PMID: 36934483
DOI: 10.1016/j.ultramic.2023.113718

Abstract

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a versatile analytical tool for characterizing materials structural properties. However, extending such analysis to disordered materials is challenging, especially in technologically important samples with mixed ordered and disordered phases. Here, we present a new 4D-STEM method, called fluctuation cepstral STEM (FC-STEM), based on the fluctuation analysis of cepstral transform of diffraction patterns. The peaks in the associated transformation relate to inter-atomic distances in a thin sample. By varying the real-space range over which fluctuations are calculated, distinct ordered and disordered phases can be mapped in a diffractive image reconstruction. We demonstrate the principles of FC-STEM by characterizing a silicon anode, harvested from a cycled lithium-ion battery. A mixture of amorphous and nanocrystalline silicon, graphitic carbon, and electrolyte by-products is identified and mapped. Comparisons with conventional electron imaging and energy-dispersive X-ray spectroscopy show that FC-STEM is highly effective for the structure determination of mixed-phase amorphous materials.

Keywords: 4D-STEM; Amorphous silicon; Disordered materials; Electron diffractiion cepstrum; Electron nanodiffraction; Fluctuation electron microscopy; Lithium-ion battery.