Nanoscale characterization of crystalline and amorphous phases in silicon oxycarbide ceramics using 4D-STEM

Abstract

Polymer-derived ceramics have great potentials in various high-temperature fields. However, lack of atomic-scale characterization and understanding of the short- to medium-range order and disorder hinders the advancement of this promising material family. In this study, poly(vinylmethylsiloxane)-derived silicon oxycarbide (SiOC) is used as a model system to address this issue. Electron diffraction-based radial distribution function (RDF) analysis is used to characterize the short- to medium-range order in the SiOC system and provide local structural data with a resolution of a few nanometers. With systematic data calibration and structural analysis, integrated 2D images from the diffraction pattern at each probe position are recorded and analyzed by the Python-based py4DSTEM toolkit; phase distributions of heterogeneous amorphous plus crystalline SiOC are obtained. This approach provides atomic-level characterization and can advance our fundamental understanding of the SiOC formation and microstructure evolution.