Abstract: Nano-Fe3O4 particles were prepared by oxidative precipitation together with weak exterior magnetic field induction. The crystalline form，morphology and magnetic properties of the prepared particles were characterized by using XRD，SEM and VSM. The introduction of a weak magnetic field could accelerate the phase transformation of goethite (α-FeOOH) to magnetite (Fe3O4). The prepared nano-Fe3O4 particles have a spinel structure and are well crystallized. Induced by the weak magnetic field，the particles tend to be formed with a polyhedron morphology with a narrower particle size distribution and a larger diameter. Due to the changes in crystallinity，morphology and size distribution，the prepared nano-Fe3O4 particles have a higher saturation magnetization and a stronger coercive force.

摘要： 通过弱外磁场诱导氧化共沉淀法合成Fe3O4纳米粒子，并采用XRD、SEM、VMS表征产物晶型、形貌和磁性能。结果表明，弱外磁场可诱导加速α-FeOOH向Fe3O4的相转变，产物粒子为尖晶石结构，且结晶良好；产物粒子在外加弱磁场诱导后更倾向于向多面体形貌生长，且粒度分布变窄、粒径变大；产品的磁性能由于粒子晶化程度、形貌、粒度分布的变化，其饱和磁化强度、矫顽力均变大。