Fabrication of anisotropic MnBi nanoparticles by mechanochemical process

MnBi nanoparticles with size in the range 100-300 nm were fabricated from a mixture of Bi2O3 and Mn in the presence of Ca as reducing element by a mechanochemical process. Heat treatment of as-milled powder and subsequent washing yielded nanoparticles with composite morphology of MnBi/Bi. Nanoparticles were crystallographically anisotropic and displayed high remanence ratio (Mr/Ms) of 0.94 and high coercivity (Hc) of 16.3 kOe at room temperature. The spin reorientation temperature of the MnBi nanoparticles was found to be at 119 K showing an increase by 10 K as compared to the bulk sample.