Textured SnSe micro-sheets: One-pot facile synthesis and comprehensive understanding on the growth mechanism

Abstract

Preferential aligned SnSe micro-sheets were successfully synthesized via a surfactant-free hydrothermal synthesis route. The Lotgering factor F and the intensity ratio of (400) to (111) for SnSe Micro-sheets prepared by the optimized process is 0.64, 9.85, respectively, which verify the obvious textured characteristic of micro-sheets. The micro-sheets with uniform composition are polycrystallines with an orthorhombic crystal structure, show the preferential aligned morphology assembled by a great deal of nano-particles according to observation and analysis from the electron diffraction pattern, the lattice fringe, the Energy-dispersive spectroscopy and the transmission electron microscopy (TEM) images. Through deep observation from high-resolution transmission electron microscopy, an arc pattern verifies the textured characteristic of the SnSe sheet. The preferential aligned growth mechanism can be understood by researching effect of reaction temperature, alkali concentration on phase, preferred orientation and morphology. A proper temperature can control textured degree via adjusting effective diffusion, rotation of nano-crystal and fluid movement. Increasing alkali concentration enhances the surface adsorption stability of chalcogenides, and decreases new nucleation site in the (011) face, and helps the dis-matched nano-crystal re-dissolute, which results in formation of square-like textured micro-sheets. A proposed growth mechanism of textured SnSe micro-sheets with two growth models (the lateral growth model and the vertical growth model) is provided, and the two growth models control textured characteristic of micro-sheets, which can be adjusted by change of reaction temperature and alkali concentration.