Effects of Ga-doping on the microstructure and magnetic properties of MnBi alloys

Highlights: • Effects of doping Ga on the microstructural and magnetic properties of MnBi alloy. • The MnBi-Ga powders are achieved by surfactant assisted high energy ball milling. • The maximum energy produce (BH)_max shows 7.87 MGOe for Mn₅₅Bi₄₄Ga sample. • The coercivity of Mn₅₅Bi₄₀Ga₅ after ball milling reached 1.66 T at room temperature. • The elevated curie temperature (T_c) by doping Ga makes it a possible candidate for high temperature applications. The low temperature phase Mn₅₅Bi_45-xGa_x (x = 0, 1, 3, 5, and 10) alloys were prepared by induction melting process with subsequent low temperature annealing. The effects of Ga-doping on the crystal structure and magnetic properties of the alloys were systematically studied. The room temperature coercivities of Mn₅₅Bi_45-xGa_x after ball milling increased from 1.43 T for x = 0 to 1.66 T for x = 5, while the saturation magnetization decreased from 60.7 Am²/kg (x = 0) to 45.1 Am²/kg (x = 5). The maximum energy product (BH)_max of Mn₅₅Bi₄₄Ga powders reached 7.87 MGOe. The Curie temperature of the Mn₅₅Bi_45-xGa_x alloys increased from 633 K to 658 K with increasing Ga concentration in the range of 0 ≤ x ≤ 5.