Study Of The Properties For Cu（I） Modified γ-Fe₂O₃ Nanoparticles And Ferrofluids

γ-Fe₂O₃ magnetic nanoparticleswereprepared by the method of chemicallyinduced phase transition using FeCl₂ solution and FeCl₂/NaOH solution as treating solution.By transmission electron microscopy（TEM）, high resolution electron microscopy（HRTEM）, X-ray diffraction（XRD）,energydispersive X-ray spectroscopy（EDX）, X-ray photoelectron spectroscopy（XPS） and vibrating sample magnetometry（VSM）, the morphology, crystal structure, the chemical compounds and magnetizationproperties of nanoparticles were characterized and analyzed. The experimental results show that the the γ-Fe₂O₃ nanoparticles are nearly spherical particles using FeCl₂ solution, they consisted of irregular flake particles and nearly spherical particles using FeCl₂/NaOH solution. NaOH led to the formation of a γ-Fe₂O₃ epitaxial layer on the γ-Fe₂O₃ crystallites formed from precursor transition and led to an increase in specific magnetization strength with increasing NaOH concentration. But the saturation magnetization of nanoparticles is not presented monotonic changes with increasing concentration of NaOH solution. Combined with characterization data and treated nanoparticles particle size analysis, the results show that for the nanocrystallite system having lognormal distribution diameter, and had a magnetic interaction between magnetic nanoparticle system. The median particle size of effective magnetic and distribution bias can export by a digital fit. The grain size calculated using Schereer formula corresponds to the median size rather than average size.NaOH led to an increase in grain size strength with increasing NaOH concentration.By using the chemically-induced transition method with an FeCl₂ solution, γ-Fe₂O₃ nanoparticles coated with a layer of FeCl3·6H2O can be synthesized using FeOOH/Mg（OH）2 as a precursor. During the synthesis of the γ-Fe₂O₃ nanoparticles, Cu（I）-modification of the nanoparticles has been attempted by adding CuCl/NaOH to the solution. Energy dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission microscopy, X-ray diffractometry, and X-ray photoelectron spectroscopy were used to characterize the bulk chemical compounds, morphology, crystal properties, and surface chemical compounds of the as-prepared products. The magnetization curves were measured by a vibrating sample magnetometer. The experimental results showed that, under the condition of a NaOH content equal to 0.04 moles, when the content of CuCl is as low as 1.25 × 10-3 or 2.50 × 10-3 moles, the products are single γ-Fe₂O₃ /Cu（I）FeO2 /FeCl3·6H2O composite nanoparticles, whereas when the content of CuCl is higher, 5 × 10-2 moles, the product is a mixture consisting of γ-Fe₂O₃ /Cu（I）FeO2 /FeCl3·6H2O nanoparticles and Cu（II）（OH）Cl nanoparticles. For the γ-Fe₂O₃ /Cu（I）FeO2 /FeCl3·6H2O composite nanoparticles, the Cu（I）FeO2 interface layer is not thick enough to form one unit cell, but it can modify the formation of a FeCl3·6H2O surface layer and the effective magnetization of the γ-Fe₂O₃ core. In addition, the Cl and Cu spectra of Cu（OH）Cl measured by XPS have the same structure as those of CuCl₂.Carried out the synthesis of γ-Fe₂O₃/FeCl3·6H2O and Cu（I） modifying γ-Fe₂O₃/Cu（I）FeO2 /FeCl3·6H2O composite magnetic nanoparticle ionic ferrofluids using the self-formation synthesis method of ionic ferrofluids, and analyzed the magnetic properties of ferrofluids. The experimental results showed that, the saturation magnetization of the two kinds of ferrofluids are increased with the increase of mass fraction. When the mass fraction smaller（< 3.5%）, two kinds of special magnetization of ferrofluids and saturated magnetization are basically the same, and when the mass fraction increases gradually, the saturation magnetization of Cu（I） modifying γ-Fe₂O₃ based ferrofluids were obviously higher than that of γ-Fe₂O₃ based ferrofluids.This showed the CuCl solution increased the γ-Fe₂O₃ nanoparticles saturation magnetization, so as to improve the saturation magnetization of ferrofluids.