Hydrothermal/solvothermal Synthesis And Characterization Of Several Micro/nano-materials

In this thesis, Bismuth selenide(Bi₂Se₃), Bismuth oxychloride(BiOCl) and Bismuth ferrite(BiFeO₃) micro/nano-crystals were successfully prepared using hydrothermal and solvothermal method via the new reaction systems and process routes, and the structures, morphology, optical and electrical properties of those materials were characterized.Three main aspects involved in the thesis are presented as below.(1)Bi₂Se₃ single-crystal nanoplates have been successfully synthesized via a solvothermal route using a mixed solvent of ethylenediamine (EN) and ethylene glycol (EG) with the assistant of polyvinyl pyrrolidone (PVP). The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), selected area diffraction (SAED), high resolution transmission electronic microscopy (HRTEM) and Hall measurement. The results show that the Bi₂Se₃ nanoplates are single crystals and have regular hexagonal shape with 200⁶00 nm in lateral length and about 80¹60nm in thickness. The influences of solvent volume ratio and additive on the products were discussed.(2)Novel BiOCl single-crystal nanoplates have been successfully synthesized with cetyl trimethyl ammonium bromide (CTAB) as surfactant via a solvothermal route using a mixed solvent of deionized water and ethanol absolute. The BiOCl nanoplates were characterized by XRD, SEM, TEM, SAED and HRTEM. The results show that the BiOCl nanoplates have diameters ranging from 300nm to 3μm, and thickness of about 200nm. UV-Vis absorption spectrum result shows the absorption edge of the BiOCl nanoplates is about 330nm.(3)BiFeO₃ nanostructures with different morphologies were synthesized by hydrothermal and/or solvothermal process based on the reaction between BiCl3, FeCl₃, and KOH (mineralizer). The products were characterized by XRD, SEM and Fourier transform infrared spectrometry (FT-IR). The results show that the BiFeO₃ crystals have near pure phase, and the morphology of the final products are influenced by KOH amount, reaction temperature, reaction time and the additive.