Microstructure and magnetic properties of Al-doped barium ferrite with sodium citrate as chelate agent

In this paper, M-type Al-doped barium ferrites were successfully synthesized using sodium citrate (SC) as the chelate agent by a chemical process complemented by a suitable thermal treatment of the precursor. It was found in TGA/DTA and XRD analysis that the crystallization and formation of single phase BaM had completed before 860 degrees C. The XRD data also confirmed Al substituting into Fe sites. Meanwhile, it can be seen from the SEM images that the particle size and morphology were not affected by Al doping. However, Al substitution played an important role on the magnetic properties. The saturation magnetization (M-s) of BaAlxFe12-xO19 decreased from 51.43 emu/g for the sample with x=0 to 28.32 emu/g at x=1.5. The anisotropy field (H-a), however, increased from 16.21 kOe to 25.01 kOe. In addition, M-s increased with enhancing the ratio of SC/Ba2+ (molar ratio), reaching a maximum when SC/Ba2+ was 13. (C) 2013 Elsevier B.V. All rights reserved.