High-energy ball milling of Ba-hexaferrite/Fe composite

P. G. BERCOFF; H. R. BERTORELLO

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

Elsevier

Lugar: Amsterdam; Año: 1998 vol. 187 p. 169 - 176

0304-8853

A Ba-hexaferrite/Fe composite is synthesized using a high-energy ball mill. Changes in the crystalline structure and magnetic properties are studied with the aid of x-ray diffraction and magnetization measurements.  The product after an 80-hour mill is magnetite (Fe3O4) and barium carbonate (BaCO3). After heating up to 1300 K in air and Ar atmospheres it is found that in the former case the product is phase M (BaFe12O19) and hematite (a-Fe2O3) with improved magnetic properties while in the second, BaFe12O19 and Fe3O4 are obtained. This is a magnetic composite material having both dipolar and exchange couplings. The coercivity observed is explained in terms of the modified Brown's equation for inverse domain nucleation fields.