Fabrication of Mn-Bi Nanoparticles by High Energy Ball Milling

Abstract

The MnBi low temperature phase with high value and positive temperature coefficient of its coercivity has a potential for production of both the nanocomposite and hybrid permanent magnets. In this report, we present our results of investigation of fabrication of Mn₅₅Bi₄₅ nanoparticles by using high energy ball milling method. The Mn₅₅Bi₄₅ alloy was first arc-melted and then ball-milled for various time of 0.25–8 h in different environments of Argon, Alcohol, Petrol and Xylene. The resulted powder was subsequently annealed at temperatures of 200 and 250°C for time periods of 0.5–4 h in Ar gas. The fraction of the MnBi low temperature phase and the size of the particles strongly depend on the fabrication conditions. The desired MnBi nanoparticles with size of 25–100 nm and coercivity μ₀H_c > 1 T can be achieved by choosing appropriate fabrication conditions.