Studies on characterization, microstructures and magnetic properties of nano-size barium hexa-ferrite prepared through a hydrothermalprecipitation–calcination route

An attempt was made to prepare nano-size barium hexa-ferrite particles following a hydrothermal precipitation–calcination route using
barium and iron nitrate solutions. During hydrothermal treatment at 180 ◦C (2 h precipitation time) barium carbonate and hematite phases
were formed. This precursor was calcined at 800, 1000 and 1200 ◦C to determine the conditions for obtaining barium hexa-ferrite. The
characterization studies on calcined products revealed that up to 800 ◦C, the major crystalline phases (barium carbonate and hematite) of
the precursor were retained. At 1000 ◦C, formation of barium hexa-ferrite started and at 1200 ◦C, though most of the major peaks of X-ray
diffractogram corresponded to barium hexa-ferrite, a number of peaks corresponding to hematite were also present. Some low intensity
peaks for barium carbonate were observed. The average particle size was 40 nm. Saturation magnetization, remanence magnetization and
coercivity were found to be 40.0, 21.6 emu g−1 and 2.87 kOe, respectively. The values obtained both for coercivity and magnetization for
the present sample were lower than the reported bulk values which could be due to the fact that the sample prepared through the present
technique was not mono-phasic.