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

The phase formation and magnetic property evolution processes of the hexaferrite with composition BaO center dot 0.9Sc(2)O(3)center dot 5.1Fe(2)O(3) have been investigated. Results show that when the calcination temperature is lower than 1000 degrees C, the spinel phase BaFe2O4 and M-type hexaferrite phase BaFe12O19 dominate. The M-type hexaferrite BaFe12-xScxO19 (0 < x <= 1.8) appears above 1050 A degrees C and becomes a single phase BaFe10.2Sc1.8O19 above 1200 A degrees C. A two-step decrease of both the coercivity and remanence ratio is observed above 1050 degrees C, which agrees well with the appearance of soft magnetic phase BaFe12-xScxO19 (0 < x <= 1.8). The saturation magnetization of the sample increases with calcination temperature until 1100 degrees C and then decreases. Raman spectra results show that the above magnetic property evolutions can be explained by a temperature dependent incorporation of Sc3+ into the lattice sites nearby the magnetic blocks' interfaces. This weakens the local magnetic exchange interactions between Fe3+ and thus leads to a change in the magnetic structure.