Research On The Preparation Of Iron Oxide Nano-materials

In this dissertation,the preparation methods of α-Fe2O3, Fe3O4, MnFe2O4, BaFe12O19(SrFe12O19) were analyzed,and the effects on the preparation of nanopowders by different surfactants were investigated.The best preparation conditions have been determined.(1)The preparation method of α-Fe2O3 nanopowders:Firstly,choosing dodecylbenzene sulfona(SDS) to prepare α-Fe2O3 from 30 surfactants by sedimentation experiments. With FeCl3·6H2O as raw materials,adding SDS at the mass of 2% FeCl3·6H2O,adding water and stirring,mixing solid NaOH in and stirring,drying,roasting in 400℃ and keeping this condition for 1 hour, after cooling, washing with water,drying. The final products are characterized by X-ray diffraction(XRD) and transmission electron microscopy(TEM).XRD analysis shows that the ingredient is α-Fe2O3, crystalline is good, purity is high.TEM analysis shows that the morphology of the α-Fe2O3 nanopowders is spherical grains with the size about 30 nm.The dispersing experiments show that sorbitan monopalmitate and alkyl ether phosphate salts have good dispersion to α-Fe2O3 nanopowders.It can form a water sol of α-Fe2O3 nanoparticles.(2)The preparation method of Fe3O4 nanopowders: choosing arab resin to prepare Fe3O4 from 30 surfactants by sedimentation experiments.Acordding to proportion n(Fe3+)/n(Fe2+)=(1.0~1.5):1, With FeCl3·6H2O and FeSO4·7H2O as raw materials, adding water and stirring,mixing NaOH solution to adjust pH to10.Black Fe3O4 nanopowders have been produced.The products are characterized by X-ray diffraction(XRD) and transmission electron microscopy(TEM).XRD analysis shows that the ingredient is Fe3O4, crystalline is good, purity is high. TEM analysis shows that the size of Fe3O4 nanopowders is about 20 nm,and the distribution of nanopowders is uniform,but with slight agglomeration. The dispersing experiments show that water-soluble oil and dimethyl hydroxyethyl quaternary ammonium nitrate have good dispersion to Fe3O4 nanopowders.It can form a water sol of Fe3O4 nanoparticles.(3)The preparation method of MnFe2O4 nanopowders: MnFe2O4 nanopowders have been produced each by hydroxide precursor, carbonate precursor and oxalate precursor, The sedimentation experiments show that samples produced by carbonate precursor with the slowest settlement speed,while oxalate precursor is the fastest. The final products are characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM).Carbonate precursor roasted in 400℃, XRD analysis shows that MnFe2O4 nanopowders are pure phase. SEM analysis shows that the morphology of the α-Fe2O3 nanopowders is spherical grains with the size about 40 nm.(4)By contrast BaFe12O19(SrFe12O19) produced by different raw materials,the conclusion is that the best method is using FeCl2,FeCl3 to generate Fe3O4,then producing BaFe12O19(SrFe12O19). The products are characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM).The size of BaFe12O18 nanopowders with span-20 surfactant is about 100 nm,while SrFe12O19 nanopowders with fatty alcohol ethoxylates surfactant is 50-250 nm.