| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1489019 | Materials Research Bulletin | 2013 | 7 Pages |
•Exchange-spring behaviour of soft and hard ferrites was studied.•XRD patterns indicated soft and hard ferrites as fcc and hcp structure.•Hysteresis loops indicate wide difference in coercivity of soft and hard phases.•Nanocomposites produced convex hysteresis loop characteristic of single-phase.
The paper reports exchange-spring soft and hard ferrite nanocomposites synthesized by chemical co-precipitation with or without the application of ultrasonic vibration. The composites contained BaFe12O19 as the hard phase and CoFe2O4/MgFe2O4 as the soft phase. X-ray diffraction patterns of the samples in the optimum calcined condition indicated the presence of soft ferrites as face-centred cubic (fcc) and hard ferrites as hexagonal close packed (hcp) structure respectively. Temperature dependence of magnetization in the range of 20–700 °C demonstrated distinct presence of soft and hard ferrites as magnetic phases which are characterized by wide difference in magnetic anisotropy and coercivity. Exchange-spring mechanism led these nanocomposite systems to exchange-coupled, which ultimately produced convex hysteresis loops characteristic of a single-phase permanent magnet. Fairly high value of coercivity and maximum energy product were observed for the samples in the optimum calcined conditions with a maximum applied field of 1600 kA/m (2 T).
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