中文摘要：

用改进的共沉淀法制备粒径范围为（25±5）nm的磁性Fe3O4纳米粒子，采用不同温度真空干燥以及自然晾干2种常规方法对磁性Fe3O4纳米粒子进行干燥处理，获得了磁性Fe3O4纳米粉体，重点研究了采用不同干燥方法对纳米粉体各种性能的影响，并对其物理化学机理进行了分析。利用X射线粉末衍射仪（XRD），透射电子显微镜（TEM），带有能谱仪（EDS）的扫描电子显微镜（SEM），光电子能谱仪（XPS），热重分析仪（TGA），以及带有超导量子干涉仪（SQUID）的磁学测量系统（MPMS）对纳米粉体的结构和性能进行了表征和分析。结果表明：真空干燥处理获得粉体的粒径分布范围由于表面吸附自由水和团聚粒子间吸附水的蒸发而减小，但粒子更易产生团聚，而采用自然干燥处理的Fe3O4纳米粉体在结构和形态方面保持最好；采用T=70℃真空干燥处理的Fe3O4纳米粉体的磁学性质保持最好；Fe3O4纳米粉体结构和磁学性能的影响与干燥温度和干燥方式有关。

英文摘要：

Magnetite Fe3O4 nanopowders of about （25±5） nm were prepared by modified chemical co-precipitation, and corresponding properties and structure were studied thoroughly when they are treated under different drying conditions. The nanopowders were characterized by X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） with the energy dispersive spectroscopy （EDS）, transmission electron microscopy （TEM）, thermogravimetry analysis （TGA）, X-ray photoelectron spectroscopy （XPS） and magnetic property measurement system （MPMS） with superconducting quantum interference device （SQUID） magnetometry. The result reveals that the nanopowders by vacuum drying tend to be agglomerated more easily when the grain average diameter is decreased in pace with the evaporation of the surface adsorptive water and inner containing water, though the structure and morphology are maintained better by ambient air drying. Among all the drying treatments, the best magnetic property is maintained as the vacuum drying temperature is T=70 ℃. Thus the drying treatments and methods are closely related to the Fe3O4 nanopowders＇ morphology and magnetic property. The finding is instructive to elucidate in depth some relationship between nanopowders＇ structure and property.