用共沉淀法制备了Ni-Fe氧化物复合磁性纳米微粒,并采用Massart法合成了无表面活性剂的离子型磁性液体。用X射线衍射仪(XRD)、X射线能谱仪(EDX)、X射线光电子能谱仪(XPS)、透射电子显微镜(TEM)分别对其微粒结构及粒径进行分析,并用HH-15振动样品磁强计(VSM)测量了磁性微粒和磁性液体的磁化强度,分别用Langevin理论和类气压缩模型对磁性液体磁化曲线进行拟合。实验结果表明,Langevin理论曲线与实验曲线有较大偏差,而类气压缩模拟的曲线与实验曲线拟合的较好,且压缩参数γ随磁性液体体积分数的增大而增大。应用场致团聚效应解释了Ni2O3/γ-Fe2O3磁性液体的磁化性质。
Ni-Fe oxide composite magnetic nanoparticles prepared by chemical co-precipitation method are introduced and ionic ferrofluids without surface-active agent is made by Massart method. The microstructure and grain size are analyzed through XRD, EDX, XPS and TEM, and the magnetization vs. magnetic field is measured by vibrating sample magnetometer (VSM, HH-15). The magnetizing curves have been fitted by using Langevin theory and gas-like compression model, respectively. The results indicate that there is an obvious deviation between Langevin theory and experimental data while the gas-like compression model can fit well, and that the compression parameter γ increases with the increasing ferrofluids volume fraction. The magnetization behaviors of Ni2O3/γ-Fe2O3 ferrofluids can be well illustrated by the field induced aggregation effect.
[1] Odenbach S. Ferrofluids-magnetically controlled suspensions[J]. Colloids Surfaces A, 2003, 217(1-3):171-178.
[2] Sousa M H, Tourinho F A, Depeyrot J, et al. New electric double-layered magnetic fluids based on copper, nickel, and zinc ferrite nanostructure[J]. Journal of Physical Chemistry B, 2001, 105(6):1168-1175.
[3] Faraudo J, Andreu J S, Camacho J. Understanding diluted dispersions of superparamagnetic particles under strong magnetic fields:A review of concepts, theory and simulations[J]. Soft Matter, 2013, 9(5):6654-6664.
[4] Massart R. Preparation of aqueous magnetic liquids in alkaline and acidic media[J]. IEEE Transactions on Magnetics, 1981, 17(2):1247-1248.
[5] Zhang Q M, Li J, Lin Y Q, et al. The preparation and characterization of Ni-Fe bioxide composite nanoparticles[J]. Journal of Alloys and Compounds, 2010, 508(2):396-399.
[6] Popplewell J, Sakhnini L. The dependence of the physical and magnetic properties of magnetic fluids on particle size[J]. Journal of Magnetism and Magnetic Materials, 1995, 149(1):72-78.
[7] Li J, Huang Y, Liu X D, et al. Effect of aggregates on the magnetization property of ferrofluids:A model of gaslike compression[J]. Science and Technology of Advanced Materials, 2007, 8(6):448-454.
[8] Huke B, Lücke M. Magnetic properties of colloidal suspensions of interacting magnetic particles[J]. Reports on Progress in Physics, 2004, 679(2):1731-1768.
[9] Takctomi S, Drew R V, Shull R D. Peculiar magnetic aftereffect of highly diluted frozen magnetic fluids[J]. Journal of Magnetism and Magnetic Materials, 2006, 307(1):77-84.
[10] Camp P J, Patey G N. Structure and scattering in colloidal ferrofluids[J]. Physical Review E, 2000, 62(4):5403-5408.
[11] Xu C, Ma Y Q, Hui P M, et al. Microstructures in strongly interacting dipolar fluids[J]. Chinese Physics Letters, 2005, 22(2):485-488.
[12] Satoh A, Sakuda Y. Rheology and orientational distributions of rodlike with magnetic moment normal to the particle axis for semi-dense dispersions (analysis by means of mean field approximation)[J]. Journal of Colloid and Interface Science, 2007, 308(2):532-541.
[13] Li J, Li D C. The bidispersed model system and binary system for ferrofluids[J]. Physics International, 2012, 3(1):28-43.
[14] Blanco-Mantecón M, O-Grady K. Interaction and size effects in magnetic nanoparticles[J]. Journal of Magnetism and Magnetic Materials, 2006, 296(2):124-133.