The effects of synthesis variables on the magnetic properties of coprecipitated barium ferrite powders

Barium ferrites (BaFe12O19) are largely used for permanent magnets, mostly because of the adequate combination of low cost and good magnetic properties. These ferrites are usually obtained by the ceramic method, however, many chemical methods have been investigated. Among these methods, the coprecipitation is the most suitable, mainly because of its simplicity as compared to the other ones. In this work, BaFe12O19 was prepared by coprecipitation, changing the sequence of addition of the reagents, and the calcination temperature and time. The X-ray diffraction patterns of the calcined samples show the formation of BaFe12O19 at temperatures as low as 800degreesC. The ferrite powders obtained by coprecipitation have better magnetic properties than those obtained by the ceramic method, with an intrinsic coercivity value of 440 kA/m (5.5 kOe). (C) 2002 Elsevier Science B.V. All rights reserved.