The Research On Synthesis Of Ferrite Nanoparticles Via Ultrasonic Wave-assisted Aqueous Ball Milling Technology

The research on the influence of ultrasonic to the preparation of ferrites wascarried out by milling NiCO₃·2Ni（OH）₂·4H₂O, MnO₂and Co₂O₃in aqueous solutionusing small iron milling balls as the supply of Fe source. The products ofNiCO₃·2Ni（OH）₂·4H₂O, MnO₂and Co₂O₃milled with ultrasonic assistance werecompared using small iron balls （the iron balls provide Fe source） and small stainlesssteel balls（adding Fe powder as Fe source）, respectively. The phase constitution, theparticle size, the morphology and the magnetization of the as-milled products werecharacterized by X-ray diffraction, particle size analyzer, transmission electronmicroscopy and vibrating sample magnetometer, respectively. Also, well-orderedNiFe₂O₄and MnFe₂O₄nanoparticles were directly synthesized using small ironmilling balls at the temperature lower than100℃in a relatively short period of timeby ultrasonic-assisted aqueous ball milling technology without subsequent calcination.Compared with conventional process, the new technique was simple and environmentfriendly to obtain function ferrite nanopowders without active agents and dispersant.The results were listed as follows:（1） Ellipsoidal nickel ferrite particles were directly synthesized at lowtemperature of≤100°C in20h, without the need of calcination, via ultrasonic-assistedaqueous ball milling technique using NiCO₃·2Ni（OH）₂·4H₂O as raw material andsmall iron balls as milling balls. However, only amorphous Fe2Ni2（OH）8CO₃·2H₂Owas obtained when NiCO₃·2Ni（OH）₂·4H₂O milled without ultrasonic assistance for40h. Pure NiFe₂O₄phase was also obtained by ultrasonic-assisted aqueous ball millingtechnology using NiCO₃·2Ni（OH）₂·4H₂O and Fe powder as raw materials and smallstainless steel balls as milling balls. When the milling time was prolonged, some Fepowder was remnant due to the abrasion of the stainless steel balls. The products ofNiO milled with ultrasonic assistance for60h were NiO, Fe2O₃and a small amount ofNiFe₂O₄using small iron balls. Ultrasonic wave can induce the generation of NiFe₂O₄when using NiCO₃·2Ni（OH）₂·4H₂O as raw material.（2） Flaky MnFe₂O₄particles were synthesized via ultrasonic-assisted aqueousball milling technique for30h using MnO₂as raw material and small iron milling balls.However, the products were MnO₂, Fe3O4and a small amount of MnFe₂O₄whenMnO₂milled without ultrasonic for40h. Ultrasonic wave can accelerate the generation of MnFe₂O₄. MnFe₂O₄and Fe were obtained by ultrasonic-assistedaqueous ball milling technology using MnO₂and Fe powder as raw materials, smallstainless steel balls as milling balls.（3） Pure CoFe₂O₄was still not obtained when Co₂O₃ball milled with ultrasonicassistance for40h using small iron milling balls, the products are mainly CoFe₂O₄,Fe3O4and Fe2O₃. However, the products milled without ultrasonic assistance for50hare mainly Co3O4、Fe3O4and CoFe₂O₄. The products of Co₂O₃and Fe mixture milledwith ultrasonic assistance for50h are mainly Fe3O4、Fe and CoFe₂O₄using smallstainless steel balls. Ultrasonic has little effect on the generation of CoFe₂O₄.