Effect of annealing temperature on the structural and magnetic properties of barium hexaferrite powders prepared by a modified co-precipitation technique

We report studies on the influence of the temperature of a high-temperature treatment on the microstructural and magnetic properties of nanosized single-domain BaFe12O19 powders synthesized by the modified co-precipitation method. The average particle size decreased from 90 nm to 25 nm as the synthesis temperature was decreased from 900 oC to 800 °C; also, they did not exhibit the well-defined hexagonal shape that is characteristic for the hexaferrites. The value of the saturation magnetization Мs measured was very high, namely, 61.24 emu/g. The coercivity Hc of the powders ranged from 44 Oe to 103 Oe, which indicated that the particles were in a near-superparamagnetic state. © 2016 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.