Microstructure and improved coercivity of Mn1.33Ga nanoflakes by surfactant-assisted ball milling

In recent years, Mn_xGa alloys with tetragonal structure have attracted much attention because of the erratic fluctuation of rare earth supply and especially the tunable magnetic properties from fer-rimagnetic to ferromagnetic by varying Mn content. It is theoretically estimated that MnGa compound in L1₀ structure owes high anisotropy constant K_u of 26 Mergs/cm³ and magnetization Ms of 845 emu/cm³, and thus can be regarded as a potential candidate for rare-earth-free permanent magnets. At present, surfactant-assisted high-energy ball milling (HEBM) method has been regarded as one of the effective ways to realize high coercivity for magnetic materials with large anisotropy. It was reported that high-aspect-ratio single-crystal or textured polynanocrystalline flakes of Sm-Co-based permanent magnetic materials with a submicron or nanosize thickness and high coercivity can be achieved. In this study, textured rare-earth-free Mn_1.33Ga polycrystalline nanoflakes were prepared by surfactant-assisted HEBM in heptane with 15wt. % oleic acid (OA), and the effects of milling time on structure and magnetic properties were also investigated.