Synthesis of dimorphic MR fluid containing NiCo nanoflowers by the polymer assisted polyol method and study of its magnetorheological properties

Flower-like nanostructures of NiCo (1:1) in the presence of Jeffamine was synthesized by homogeneous nucleation in 1, 2-propanediol for 3 h. Morphological characterizations performed by scanning and transmission electron microscopy (FESEM and TEM) revealed the average size distribution of 700 nm containing 2D nanosheets of ~30 nm thickness. The nanoflowers crystallize exclusively in face-centered cubic structures and were confirmed by x-ray diffraction studies. Various factors, including nature of polyol, concentrations of base and metal salts in precursor proved to affect the geometry of nanoflowers. Magnetic studies revealed the ferromagnetic nature of NiCo nanoflowers with high saturation magnetization and low coercivity (108.6 emu/g and 78.4 Oe). The enhanced shear properties and yield stress of dimorphic MR fluid containing nanoflowers of NiCo in ferrofluids can be attributed to stronger microstructure formation in the presence of magnetic field.