τ-MnAl with high coercivity and saturation magnetization
In this paper, high purity τ-Mn54Al46 and Mn54−xAl46Cxalloys 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 and magnetic measureme...
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Veröffentlicht in: | AIP advances 2014-12, Vol.4 (12), p.127113-127113-11 |
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Sprache: | eng |
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Zusammenfassung: | In this paper, high purity τ-Mn54Al46 and Mn54−xAl46Cxalloys 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 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 μB 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 μB at a volume expansion rate of ΔV/V ≈ 20%. |
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ISSN: | 2158-3226 2158-3226 |
DOI: | 10.1063/1.4903773 |