Phase formation and magnetic property evolution processes of the hexaferrite with composition BaO⋅0.9Sc 2 O 3 ⋅5.1Fe 2 O 3

The phase formation and magnetic property evolution processes of the hexaferrite with composition BaO⋅0.9Sc 2 O 3 ⋅5.1Fe 2 O 3 have been investigated. Results show that when the calcination temperature is lower than 1000 °C, the spinel phase BaFe 2 O 4 and M-type hexaferrite phase BaFe 12 O 19 dominate. The M-type hexaferrite BaFe 12−x Sc x O 19 (0 < x ≤ 1.8) appears above 1050 °C and becomes a single phase BaFe 10.2 Sc 1.8 O 19 above 1200 °C. A two-step decrease of both the coercivity and remanence ratio is observed above 1050 °C, which agrees well with the appearance of soft magnetic phase BaFe 12−x Sc x O 19 (0 < x ≤ 1.8). The saturation magnetization of the sample increases with calcination temperature until 1100 °C and then decreases. Raman spectra results show that the above magnetic property evolutions can be explained by a temperature dependent incorporation of Sc 3+ into the lattice sites nearby the magnetic blocks’ interfaces. This weakens the local magnetic exchange interactions between Fe 3+ and thus leads to a change in the magnetic structure.