Shape-controlled synthesis and growth mechanism of one-dimensional nanostructures of trigonal tellurium

Single crystalline one-dimensional (1D) nanostructures of trigonal tellurium (t-Te) with well-controlled shapes and sizes were synthesized by the hydrothermal reduction of Na2TeO3 in a mixed solution of ethanol and water at 100degreesC. The formation of various 1D nanostructures of t-Te was mainly determined by properly controlling the nucleation and growth rate of t-Te in different reaction media. In acidic solution (1 M of HCl), the reaction gave nanowires with diameters of similar to30-100 nm, while in alkaline solution (1 M of NaOH), it yielded tubular crystals with diameters of similar to1-2 mum. The diameters of tubular crystals could also be controlled by adjusting the NaOH concentration. When polymer surfactant poly( vinyl pyrrolidone) (PVP) was presented in the alkaline solution, the reaction would produce uniform nanowires with diameters of similar to25 nm. Based on the TEM and SEM studies, the formation mechanisms for these 1D nanostructures were rationally interpreted. The crystallinity of the nanowires and the tubular crystals were determined by HRTEM, ED, and XRD.