Thermodynamics and Kinetics in Anisotropic Growth of One-Dimensional Midentropy Nanoribbons

One-dimensional(1D) materials demonstrate anisotropic in-planephysical properties that enable a wide range of functionalities inelectronics, photonics, valleytronics, optoelectronics, and catalysis.Here, we undertake an in-depth study of the growth mechanism for equimolarmidentropy alloy of (NbTaTi)(0.33)S-3 nanoribbonsas a model system for 1D transition metal trichalcogenide structures.To understand the thermodynamic and kinetic effects in the growthprocess, the energetically preferred phases at different synthesistemperatures and times are investigated, and the phase evolution isinspected at a sequence of growth steps. It is uncovered that thedynamics of the growth process occurs at four different stages viapreferential incorporation of chemical species at high-surface-energyfacets. Also, a sequence of temperature and time dependent nonuniformto uniform phase evolutions has emerged in the composition and structureof (NbTaTi)(0.33)S-3 which is described based onan anisotropic vapor-solid (V-S) mechanism. Furthermore,direct evidence for the 3D structure of the charge density wave (CDW)phase (width less than 100 nm) is provided by three-dimensional electrondiffraction (3DED) in individual nanoribbons at cryogenic temperature,and detailed comparisons are made between the phases obtained beforeand after CDW transformation. This study provides important fundamentalinformation for the design and synthesis of future 1D alloy structures.