Preparation Of SiC Nanomaterials By Solvothermal Pyrolysis Of Polymethylsilane

As a wide band-gap semiconducting materials, silicon carbide (SiC)nanomaterials are widely attractive in the field of electronics, optoelectronics,nanocomposites, energy resources, life science and medicine due to their specialstructures and remarkable physicochemical properties (such as high hardness andstrength, low density, excellent resistance to oxidation and corrosion). In this study,we develop a solvothermal method to synthesize SiC quantum dots (QDs) bypyrolysis of polymethylsilane (PMS) without activator in solution. And a similarprocess was used to synthesis SiC nanowires under different conditions. Thecomposition, structures and physicochemical properties of the nanostructure wereinvestigated in details.SiC QDs grafted with Si-CH3groups have been prepared by pyrolysis of PMS intoluene at550°C. The QDs with diameters in the range of2.5-5.0nm shows wideexcitation wavelength (250-400), strong fluorescence intensity, strong resistanceagainst photobleaching over long time, and good stability in acidic and alkalineenvironment. The specimens obtained at550°C with different duration were studiedfor their luminescent properties and unique morphology. The results show that the sizeof the QDs is rarely changed and the concentration of QDs increases with increasingduration. The highest quantum yield of QDs (duration is1hour at550°C) could be92%, which will decrease in the condition of reducing or extending duration.The nanofakes, nanospheres, nanowires and QDs were prepared in the differentexperimental system at550°C in toluene. Amang the above nanostructures, thenanowires can be prepared when the PVP, ethanol, silicon wafer, and ceramic boatwere introduced into experimental system or the duration at550°C was increased to10h. The evidences from HRTEM, SAED, FTIR and XPS indicated that thenanostructures were mainly consisted of Si and C element with smll amount of Oelement, and the nanostructures were amorphous except QDs. The results could beattributed to the different reaction conditions of solvothermal route. The productshave strong photoluminescence centered at410-430nm under excitation wavelengthof350nm, which shows concrete quantum confinement effects.