Study Of Property And Preparation Of γ-Fe₂O₃/Ni₂O₃ Composite Nanoparticles And Ferrofluids

In this paper, FeOOH/Ni(OH)2 nanoparticles are prepared by chemical co-precipitation, followed by using FeCl2 solution treating the precursor in autoclave and in atmosphere, theγ-Fe2O3/Ni2O3 composite nanoparticles can be obtained.The precursor and the as-prepared nanoparticles are characterized by XRD, TEM, EDX, XPS and VSM. Using heat treatment in FeCl2 solution in atmosphere and in autoclave, a transition took place in which in addition to the Ni(OH)2 partially dissolving, the precursor was transformed intoγ-Fe2O3/Ni2O3 composite nanoparticles of about 10 nm diameter. The sample treated in FeCl2 solution is ferrimagnetic and the specific saturation magnetizationσs of the ferrimagnetic samples can be estimated 344.68 kA/m.The magnetization of singleγ-Fe2O3/Ni2O3 ferrofluids and binary ferrofluids ofγ-Fe2O3/Ni2O3—Fe2O3 were be measured, the results indicate that the experiment value of magnetization of singleγ-Fe2O3/Ni2O3 ferrofluids is approach to the the theory value, which is used the magnetization of the particle untreated by Fe(NO3)3 solution multiplied by the volume fraction of particle, while larger than the particle treated by Fe(NO3)3 solution. It is because that the ring-like aggregates are formed in the process of treating in Fe(NO3)3 solution. For the volume fraction ofγ-Fe2O3/Ni2O3 ferrofluids are 0.2 percent, the magnetization of binary ferrifluids was enhanced by the volume fraction of weak ferrifluids when it is smaller 0.4%, while decreased by the volume fraction of weak ferrifluids when it is larger than 0.4%. while for binary ferrofluids which the volume fraction ofγ-Fe2O3/Ni2O3 is 0.4 percent, the magnetization of binary ferrifluids were smaller than the magnetization of the same volume fraction ofγ-Fe2O3/Ni2O3. From the point of view of aggregates induced by magnetic field, the phenomenon could be explained.To study the transmitted light through the single ferrifluids and binary ferrofluids at applied magnetic field of 300Gs,500Gs,900Gs,1300Gs, the results show that single Y-Fe203/Ni203 ferrofluids are sensitive to magnetic field, and the light transtimitted ratio of ferrofluids are relative to the volume fraction of nanoparticles in ferrofluids and magnetic field. One significant result is that the binary ferrifluids were modified by the weak magnetic ferrifluids system, and the modification effect is relative to the volume fraction of weak magnetic ferrifluids system and applied magnetic field. In addition, the ratio of transmitted light induced by field of binary ferrifluids depends on the microstructure variation of nanoparticle in ferrifluids, it is the main factor to give rise to the modification effect of weak magnetic ferrifluids system to the ratio of transmitted light variation induce by applied magnetic of binary ferrifluids According to the model of formation of nanoparticles chain and movement, it were analysized the microscopy mechanical of transmitted light through the film of composite ferrofluids and binary ferrofluids. It is explained by the model of particle chain formation and movement in ferrifluids under applied magnetic field.