The anisotropic sublimation induces rhombohedral to rock-salt phase transformation of chalcogenide SnSb2Te4 two-dimensional nanomaterial

Abstract

We report the sublimation and phase transformation mechanisms of a two-dimensional (2D) chalcogenide SnSb₂Te₄ using a lab-developed in-situ electro-thermal testing system on a C_s-corrected transmission electron microscope. It reveals that the sublimation process is primarily governed by the surface energy mechanism, following an anisotropic route. The van der Waals (vdW) layers ending with Te atoms lead to the preferential sublimation on (003) plane, with the (1 $\bar{1}$ 4) and (1$17$) planes accommodating the sublimation. It is uncovered for the first time, that the preferential and accommodated sublimation of Te and Sb atoms along the vdW planes results in short-range diffusion inducing a phase transition from rhombohedral SnSb₂Te₄ to rock-salt (Sn_1-xSb_x)Te. These results highlight complex physics processes of 2D materials under service conditions and the route of atomic-resolved electro-thermal research platforms for investigations of complex atomistic mechanisms of 2D materials by thermal-electric external fields.