Authors

Abstract

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a versatileanalytical tool for characterizing materials structural properties. However, extending suchanalysis to disordered materials is challenging, especially in technologically important sampleswith mixed ordered and disordered phases. Here, we present a new 4D-STEM method, calledfluctuation cepstral STEM (FC-STEM), based on the fluctuation analysis of cepstral transform of diffraction patterns. The transformation signals in the form of quefrency signal peaks relates tothe inter-atomic distances in a thin sample. By varying the quefrency range over whichfluctuations are calculated, distinct ordered and disordered phases can be mapped in a diffractiveimage reconstruction. We demonstrate the principles of FC-STEM by characterizing a siliconanode, harvested from a cycled lithium-ion battery. A mixture of amorphous and nanocrystallinesilicon, amorphous carbon, and electrolyte by-products is identified and mapped. Comparisonswith conventional electron imaging and energy-dispersive X-ray spectroscopy show that FCSTEM is highly effective for the structural determination of mixed-phase amorphous materials.