A study on the formation of strontium hexaferrite nanopowder by a sol-gel auto-combustion method in the presence of surfactant

Strontium hexaferrite is a hard magnetic material and has been extensively used as a permanent magnet. In this work, a novel sol-gel auto-combustion method was used to synthesize ultra-fine strontium hexaferrite, and the effect of the surfactant on the crystallite size of the final product was investigated for the first time. The DTA/TGA plot exhibited the formation temperature of hexaferrite. The XRD results show that adding surfactant to the sol does not change the composition of the combustion product and the surfactant burns completely during the combustion process. The average crystallite size of hexaferrite powders was also measured by the X-ray line broadening technique employing the Scherrer formula. The results show that adding surfactant to the gel makes the particle size of the final product much smaller. (C) 2005 Elsevier B.V. All rights reserved.