Ga-based magnetic fluid with Al2O3-coated Ni nanoparticles

Abstract

Five kinds of metal-based magnetic fluids were prepared by dispersing different kinds of Ni nanoparticles (NPs) into liquid Ga: (a) neat Ni NPs, (b) Al₂O₃-coated Ni NPs, (c) SiO₂-coated Ni NPs, (d) Ni NPs after 573 K heat treatment, (e) Ni NPs after 673 K heat treatment. The stabilities and magnetic properties of the five different magnetic fluids were characterized. The saturation magnetizations of the magnetic fluids with Al₂O₃-coated and SiO₂-coated Ni NPs are 1.56 emu g⁻¹ and 1.36 emu g⁻¹, respectively, higher than 0.81 emu g⁻¹ and 0 emu g⁻¹, which are the saturation magnetizations of magnetic fluids with Ni NPs after 573 K and 673 K heat treatment respectively. Furthermore, the results of magnetic weight experiments show that the magnetic fluid with Al₂O₃-coated Ni NPs and magnetic fluid with Ni NPs after 573 K heat treatment have less magnetic loss. It can be concluded that Ga-based magnetic fluid with Al₂O₃-coated Ni NPs has both high magnetic properties and strong stability, which is suitable for practical applications. Compared with the 673 K heat treatment, the 573 K heat treatment of Ni NPs also enhances the stability of the magnetic fluid with relatively less magnetic property loss.