Barium hexaferrite nanoparticles: Synthesis and magnetic properties

Carbon combustion synthesis is applied to rapid and energy efficient fabrication of crystalline barium hexaferrite nanoparticles with the average particle size of 50-100 nm. In this method, the exothermic oxidation of carbon nanoparticles with an average size of 5 nm with a surface area of 80 m(2)/g generates a self-propagating thermal wave with maximum temperatures of up to 1000 degrees C. The thermal front rapidly propagates through the mixture of solid reactants converting it to the hexagonal barium ferrite. Carbon is not incorporated in the product and is emitted from the reaction zone as a gaseous CO(2). The activation energy for carbon combustion synthesis of BaFe(12)O(19) was estimated to be 98 kJ/mol. A complete conversion to hexagonal barium ferrite is obtained for carbon concentration exceeding 11 wt.%. The magnetic properties H(c)similar to 3000 Oe and M(s)similar to 50.3 emu/g of the compact sintered ferrites compare well with those produced by other synthesis methods. (C) 2010 Elsevier B.V. All rights reserved.