Study On Synthesis And Properties Of Cobalt-dysprosium Ferrite Magnetic Nano-particles

Ferrite magnetic nano-particles is a kind of nanometer magnetic materials, with the small size effect, interface effect, surface effect and super-paramagnetism,etc. Under the effect of magnetic field, it has lots of special characters such as optics, mechanics, magnetism, electricity and so on, which is widely used in many industries, such as high density magnetic recording medium, absorbing material, sealing, lubrication, mineral separation, catalyst and biomedical engineering, etc. With the rapid development of nano technology, the requirements of the ferrite’s physical, chemical and magnetic properties are improved, a single magnetic of ferrite magnetic nano-particles can not meet the needs of different applications of multifunctional magnetic materials. Currently, domestic and foreign relevant scholars change the ferrite’s phase composition by doping or replacement, to get the different characteristics of ferrite nano-magnetic materials, that meets different application requirements. In this study, the ferrite was doped by the rare earth element Dy and transition elements Co, the cobalt-dysprosium ferrites which have different magnetic properties were prepared, details are as follows:In this paper, different sizes of cobalt-dysprosium ferrite magnetic nano-particles were prepared in Fe2(SO4)3-xH2O, FeSO4-7H2O, CoCl2xH2O, Dy (NO3)3-xH20and NaOH as raw materials by chemical co-precipitation and changing the amount of CoCl2xH2O (wt) was introduced. It was modified by lauric acid in order to prevent the magnetic particles generate hard reunion when it was in dry. Under the conditions of a molar ratio of n (Fe2+)/n (Fe3+)/n (Dy3+)=1:2:0.011, the effect of the doping amounts of Co2+on the chemical composition, particle size, phase composition, crystal structure and magnetic properties at room temperature of the product was studied. In this experiment, X-ray fluorescence spectrometer (XRF) was used to study the main metal oxide and its content in the cobalt-dysprosium ferrite magnetic nano-particles; X-ray diffraction was used to study the phase, the average particle size and crystal structure of cobalt-dysprosium ferrite magnetic particles. Superconducting quantum interference device(SQUID) was used to test the magnetism of cobalt-dysprosium ferrite magnetic particles after surface modification at room temperature. XRF analysis results show that the main metal oxides are Fe2O3, CO3O4and Dy2O3, with the chang of the amounts of doped Co2+, the main metal oxides contents were changed, the samples are the compounds of Fe (Ⅲ)-Dy (Ⅲ)-Co (Ⅲ)-Co (Ⅱ) oxidation state; X-ray diffraction (XRD) pattern show that the main phase of cobalt-dysprosium ferrite magnetic particles is Fe3O4, its crystal is face centered cubic spinel structure and crystalline completely, with the chang of the amounts of doped Co2+, the average particle size was different, were16.03nm,13.35nm,16.64nm,17.26nm,13.92nm; SQUID test results showed that the amount of doped Co2+has important effect on the magnetic characteristics of the samples compared with the dysprosium ferrite samples which did not dope Co2+, the saturation magnetization (Ms) reduces, the coercive force (Hc) and residual magnetization (Mr) were significantly improved, at room temperature does not have super-paramagnetic.