Atomic Imaging and Thermally Induced Dynamic Structural Evolution of Two-Dimensional Cr₂S₃

In this study, facile salt-assisted chemical vapor deposition (CVD) was used to synthesize ultrathin non-van der Waals chromium sulfide (Cr₂S₃) with a thickness of ∼1.9 nm. The structural transformation of as-grown Cr₂S₃ was studied using advanced in situ heating techniques combined with transmission electron microscopy (TEM). Two-dimensional (2D) and quasi-one-dimensional (1D) samples were fabricated to investigate the connection between specific planes and the dynamic behavior of the structural variation. The rearrangement of atoms during the phase transition was driven by the loss of sulfur atoms at elevated temperatures, resulting in increased free energy. A decrease in the ratio of the (001) plane led to an overall increase in surface energy, thus lowering the critical phase transition temperature. Our study provides detailed insight into the mechanism of structural transformation and the critical factors governing transition temperature, thus paving the way for future studies on intriguing Cr-S compounds.