Key step in synthesis of ultrafine BaFe12O19 by sol-gel technique

Barium hexaferrite powders have been prepared by sol-gel technique. Different ways in heat treatment of the gel are adopted to study the factors that influence the formation mechanism, morphology and magnetic properties pf BaFe12O19. Results show that preheating the gel between 400 and 500 degrees C for several hours is a key step, it can prevent the formation of alpha-Fe2O3 intermediate and obtain ultrafine BaFe12O19 single phase with improved magnetic properties and narrow size distribution at a low temperature. The barium ferrite powder had a coercive force of 5950 Oe and a magnetization of 70 emu/g, both are in good agreement with the expected values theoretically.