Facile synthesis of hierarchically structured flower-like Fe3O4 microspheres for high-performance magnetorheological fluids

[Display omitted] •Flower-like hierarchically structured Fe3O4 microspheres were prepared using a solvothermal method.•Superparamagnetic behavior with saturation magnetization of 58.8emu/g.•The Fe3O4 microspheres-based magnetorheological (MR) fluid showed typical MR effect.•The sedimentation stability of MR fluid was greatly enhanced. In this study, flower-like Fe3O4 microspheres with hierarchical structure were prepared by a one-step solvothermal method, and the obtained flower-like Fe3O4 microspheres were adopted as a new magnetorheological (MR) material to prepare a uniform MR suspension with high performances. The synthesized samples were systematically examined using FE-SEM, TEM, TGA, XRD, XPS, BET and VSM. The prepared flower-like Fe3O4 microspheres-based MR fluid indicated typical MR properties, as evidenced by the fact that shear stress, yield stress, viscoelastic storage modulus and loss modulus of MR fluid strongly depended on magnetic field strengths. Specifically, the resultant MR fluid showed good sedimentation stability with sedimentation ratio of 86.5% in the settling period. The excellent sedimentation stability could be attributed to the unique flower-like hierarchical structure, high specific surface area and the reduced particle-fluid density mismatch.