Revealing Thermally-Induced Nanoscale Behavior in Low-Dimensional Quantum Materials Through in Situ Scanning Transmission Electron Microscopy

Low-dimensional quantum materials are under considerable investigation for exploiting their unique properties within functional devices. While these materials have been extensively studied for their properties and applications, notable gaps in terms of their thermal stability and behavior remain, particularly with respect to typical device fabrication temperatures. In this presentation, I will address these gaps and discuss the dynamic transformations of one-dimensional TaSe3 and two-dimensional violet phosphorus that describe their decomposition pathways at high temperature conditions. The studies involve in situ decomposition of the materials within a scanning transmission electron microscope, allowing the study of morphological, structural, and chemical changes that precipitate each transformation event. While heating from room temperature to 1200 °C, we discovered that one-dimensional TaSe3 nanoribbons undergo a transition to two-dimensional TaSe2, culminating in the formation of a distinctive core-shell nanostructure. Furthermore, violet phosphorus nanosheets were heated from room temperature to 420 °C and exhibited a crystalline-to-amorphous transformation at edges and within fractures propagating throughout the material. For both materials, analysis of each transformation event permits the development of a breakdown mechanism to describe the behavior witnessed. These results emphasize the need for comprehensive material analysis at elevated temperatures from the perspective of engineering design, as well as a basis of scientific merit for further material investigation.