Hexaferrite particles by coprecipitation and lyophilization

Fine strontium hexaferrite particles were prepared by lyophilization (known as freeze-drying) and coprecipitation of nitrates and chloride salts, resp ectively. The resulting powders were calcined at different temperatures bet ween 700 degrees C and 1100 degrees C. As concluded from the measured hyste resis loops at 300 K, the freeze-dried hexaferrite showed good magnetic cha racteristics, the coercivity being as high as 5690 Oe. However, coprecipita ted hexaferrite displayed poor coercivity values, around 1300 Oe at best. ( C) 1999 Elsevier Science B.V. All rights reserved.