tau MnAl with high coercivity and saturation magnetization

In this paper, high purity tau Mn54Al46 and Mn54 xAl46Cx alloys were successfully prepared using conventional arc melting, melt spinning, and heat treatment process. The magnetic and the structural properties were examined using x ray diffraction XRD , powder neutron diffraction E9, HZB and magnetic measurements. A room temperature saturation magnetization of 650.5 kAm 1, coercivity of 0.5 T, and a maximum energy product of BH max 24.7 kJm 3 were achieved for the pure Mn54Al46 powders without carbon doping. The carbon substituted Mn54 xAl46Cx, however, reveals a lower Curie temperature but similar saturation magnetization as compared to the carbon free sample. The electronic structure of MnAl shows that the Mn atom possesses a magnetic moment of 2.454 amp; 956;B which results from strong hybridization between Mn Al and Mn Mn. We also investigated the volume and c a ratio dependence of the magnetic moments of Mn and Al. The results indicate that an increase in the intra atomic exchange splitting due to the cell volume expansion, leads to a large magnetic moment for the Mn atom. The Mn magnetic moment can reach a value of 2.9 amp; 956;B at a volume expansion rate of amp; 916;V V amp; 8776; 2