Size controlled growth of barium hexaferrite platelets using salt assisted sol-gel technique

BaFe12O19 (BaM) platelets of size ranging from 0.15 to 0.90 mu m were synthesized using a salt assisted sol-gel technique. The structural and morphological characteristics of the hexaferrite particles were analyzed using the x-ray diffraction technique and scanning electron microscopy. During the high-temperature calcination process, salts like KCl, KBr, KI, and K2CO3 serve as a matrix for the formation of barium hexaferrite platelets from its precursor mixture, BaCO3, and gamma-Fe2O3. The salt matrix prevents possible particle coarsening during the high-temperature treatment and promotes the growth of plate-like shaped particles. The width and thickness of hexaferrite platelets increase with a decrease in the melting temperature of potassium halide salts. The coercivity at 300 K of the barium hexaferrite particles was analyzed as a function of the lateral dimension of platelets. Barium hexaferrite platelets of width similar to 0.20 mu m yielded a coercivity as high as 4.6 kOe and magnetization of 71 emu/g. The outlined synthesis route is suitable for realizing isolated hard ferrite platelets with improved intrinsic coercivity.