Mulberry-like NiFe₂O₄ nanospheres for smart magnetic fluid: Facile synthesis, magneto-responsive performances and sedimentation stability study

Magnetorheological (MR) fluids have been extensively studied and utilized in various fields but are still restricted for their broad applications owing to the relatively poor sedimentation stability. Herein, mulberry-like NiFe₂O₄ nanospheres were fabricated via a facile solvothermal route to fight against the sedimentation challenge. Different analytical approaches were employed to thoroughly characterize the fabricated mulberry-like NiFe₂O₄ nanospheres. The resultant NiFe₂O₄ nanospheres were suspended in silicone oil to produce the model MR suspension and its magneto-responsive properties and sedimentation stability were investigated in detail. It was revealed that the NiFe₂O₄ nanospheres-based suspension demonstrated sufficient MR responses, which can be interpreted as evidence that the increased rheological and viscoelastic properties were observed as the magnetic field intensity increased. Furthermore, the designed novel MR suspension demonstrated a superior sedimentation stability in comparison with the carbonyl iron particles-based MR system, which was positive in the practical application of MR fluids to microfluidic devices.