Non-stoichiometric zinc-doped spinel ferrite nanoparticles with enhanced magnetic property and their magnetorheology

To improve the magnetorheological (MR) performance compared to typical ferrites, non-stoichiometric zinc-doped spinel ferrite (Zn0.417Fe2.583O4) nanoparticles with a high saturation magnetization value and a truncated octahedron-like shape were synthesized using a simple thermal decomposition process with benefits of monodisperse and high crystallinity. The Zn0.417Fe2.583O4 had a high saturation magnetization value of 106 A m2/kg, which is generally higher than the other ferrites. The MR characteristics of the Zn0.417Fe2.583O4 particles dispersed in silicone oil were measured using a rotational rheometer under various magnetic field strengths. The flow curves and dynamic yield stress for the different magnetic field strengths exhibited the Herschel-Bulkley behavior with a slope of 2.0 and typical MR behavior. The sedimentation stability was further examined using Turbiscan.