Study Of Preparation, Magnetization And Magneto-optical Properties Of The Binary Ionic Ferrofluids

γ-Fe2O3nanoparticles were prepared by chemical co-precipitation-transition induced chemically method, and ZnFe2O4nanoparticles was prepared by chemical co-precipitation. γ-Fe2O3nanoparticles and ZnFe2O4nanoparticles were characterized by Using energy disperse X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), then the chemical composition, the morphology, crystal structure, magnetization properties of the nanoparticles can get. γ-Fe2O3pure ferrofluids, ZnFe2O4pure ferrofluids were synthsized by Massart or self-formation method, and γ-Fe2O3-ZnFe2O4binary ferrofluids were synthsized by equal volume of mixed method, studying their magnetization properties and magneto-optical effect.The magnetization curves of the γ-Fe2O3nanoparticles and ZnFe2O4nanoparticles were measured by VSM, which show that γ-Fe2O3nanoparticles are superparamagnetic and ZnFe2O4nanoparticles are apparent paramagnetism. The magnetization properties are difference in the two kinds of nanoparticles. The magnetization of corresponding synthesis ferrofluids of nanoparticles is similar with its nanoparticles. For volume fraction of γ-Fe203-ZnFe2O4binary ferrofluids is less than1%, when the volume fraction of the γ-Fe2O3nanoparticles is certain, changing the volume fraction ZnFe2O4nanoparticles, initial susceptibility is not a monotonous with increasing volume fraction of ZnFe2O4nanoparticle in low field magnetic. When the external magnetic field is large enough, the magnetization properties may increase with increasing the volume fraction of ZnFe2O4nanoparticle. The reason is that:in γ-Fe2O3-ZnFe204binary ferrofluids, chained particles γ-Fe2O3nanoparticles can be seen as in the "sea", which is composed by unchained particles ZnFe2O4nanoparticles. At zero field, ZnFe2O4nanoparticles influence the formation of chain and ring structure of γ-Fe2O3nanoparticle. Form chain structure will strength magnetization lead to initial magnetic susceptibility larger; form ring structure make the saturation magnetization decreases, the initial magnetic susceptibility smaller. In the case of volume fraction of ZnFe2O4nanoparticles smaller, y-Fe2O;, nanoparticles mainly form chain structure. Therefore, the initial susceptibility increases with increasing volume fraction of ZnFe2O4nanoparticles. When volume fraction of the ZnFe2O4nanoparticles larger, y-Fe2O3nanoparticles main form ring structure. So the initial susceptibility decreases with increasing volume fraction of ZnFe2O4nanoparticles.When the incident light is circularly polarized light, magneto-optical effect (birefringence and dichroism) of y-Fe2O3pure ferrofluids, ZnFe2O4pure ferrofluids and y-Fe2O3-ZnFe2O4binary ferrofluids were studied under uniform magnetic field. Experimental results show that: magneto-optical effect of y-Fe2O3pure ferrofluids relate with the volume fraction of y-Fe2O3nanoparticles and applied magnetic field; ZnFe2O4pure ferrofluids have not magneto-optical effect; magneto-optical effect of y-Fe2O3-ZnFe2O4binary ferrofluids are similar with y-Fe2O3pure ferrofluids, However, the weak magnetic ZnFe2O4nanoparticles system have modulation effect to magneto-optical effect of y-Fe203-ZnFe204binary ferrofluids. Through analysis of these experimental phenomenons, we have discussed microstructure of the ferrofluids, and studied the relation that magneto-optical effect of the ferrofluids and average length of form chain structure in external magnetic field.