The size and morphology control of Fe3O4 nanoparticles synthesized by solvothermal method using polyethylene glycol and diethylene glycol
A simple solvothermal method was used to control the size and morphology of Fe3O4 nanoparticles by changing the dosage of polyethylene glycol(PEG),the molecular weight of PEG,and the volume fraction of diethylene glycol(DEG)in the reaction system.The prepared Fe3O4 nanoparticles were characterized by SEM,TEM,XRD and VSM.The results show that the walnut shaped Fe3O4 nanospheres are composed of small grains,as the dosage of PEG-4000 increasing from 0.1 g to 1.5 g,the size of the Fe3O4 grain tends to decrease.Appropriately increasing the chain length of PEG,with the molecular weight ranging from 200 to 4 000,is beneficial for promoting the growth of Fe3O4 nanocrystals.However,further increasing the length of the chain,at a molecular weight of 20 000,results in smaller Fe3O4 nanocrystals and microspheres.Changing the volume fraction of DEG can achieve the shapes transformation of Fe3O4 nanoparticles,from rough walnut like large microspheres to smooth small microspheres,and then to regular rectangular crystals.Based on the adsorption,grafting,and steric hindrance effects of PEG and DEG,possible mechanisms for the formation of different morphology and size of nanostructures have been proposed,providing a useful reference for the controllable preparation of Fe3O4 nanoparticles.The saturation magnetization of the prepared Fe3O4 nanoparticles is about 80 emu/g,showing superparamagnetism.
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