Magnetic properties of coprecipitated barium ferrite powders as a function of synthesis conditions

Barium ferrite is widely used as a permanent magnet because of its large coercivity and low cost. The usual route to produce barium ferrites is the ceramic method. In order to overcome the detrimental milling effects in the magnetic properties, ferrite powders were obtained by coprecipitation. This method can produce high purity materials with a narrow particle size distribution. In this work, the effects of the pH during coprecipitation, the molar ratio (Fe/Ba), and calcination temperature on the magnetic properties were investigated. The products were characterized by differential thermal analysis, X-ray diffractometry, scanning electron microscopy and thermomagnetic analysis. The magnetic properties were evaluated by vibrating sample magnetometry. Very fine particles with intrinsic coercivities up to 392 kA/m (4.92 kOe) were achieved.