Research Of Properties Of ZnS Nanophase Materials Prepared By Hydrothermal/Solvothermal Method

Semiconductor nanocrystals exhibit outstanding properties totally different from those of the bulk materials due to the quantum size effect. The nanocrystals may find prospective application in many fields, such as high-speed optical calculation, optical switch, optical display and optical information storage. In this dissertation, solvothermal/hydrothermal methods have been developed futher to prepare ZnS nanomaterials and a lot of characterizations have also been done. The detail is listed as following:ZnS nanocrystals with various sizes and shapes were synthesized through solvothermal route using different solvents. It was found the phase and size of the ZnS nanocrystals were controlled by the polarity and dielectric constant of the solvents. TEM showed nanoparticles were obtained in water and organic solvents, nanosheets were obtained in ethylenediamine; XRD displayed the samples made in organic solvents were cubic, both cubic and hexagonal structures were obtained in water and ethylenediamine .Using PVA as template, ethylenediamine as solvent, through solvothermal method, synthesized ZnS organic/inorganic composite film. The result identified by TEM showed that ZnS nanoparticles with small size were well dispersed in PVA matrix. The optical properties influenced by the experimental conditions were inspected and notable quantum size effects have been shown through their UV and PL at room temperature.ZnS nanowires were synthesized using hydrothermal process with dodecylthiol as a surfactant, and the effect of the volume of dodecylthiol , the content of S2-, temperature, time and PH parameters on the morphology of products were studied. It was found that the best condition for ZnS nanowires grew was: the volume of dodecylthiol equal to water, the content of S2- twice Zn2+, T=180℃, t=12h, PH=6. Under other conditions, more particles were found in the products, and the nanowires became shorter and thicker. The optical properties of ZnS nanowires were examined by PL spectrum and UV spectrum.When the ZnS powders were synthesized by hydrothermal salt solution under high pressure, it can be found that it formed the shape like dendrite crystal, leaf crystal and sawtooth caystal. The formation of the orientation adhesion and dendrictic crystals of ZnS nanocrystallites was studied. The orientation adhesion of nanocrystallites and the dendritic crystals formed by connection of crystallites were discussed by the growth unit model of anionic coordination polyhedrons.