Efecto de la adición de Gd2O3 sobre las propiedades magnéticas de hexaferritas de estroncio

The hexaferrites (AFe 12 O 19 , A = Ba, Sr) have been used since years ago. Because of their low cost these materials continue in the market and they have not been substituted for other powerful magnets. The partial substitution of metallic elements or the use of additives in small proportions have been widely used for industrial processes in order to improve magnetic properties or the sintering process. Efforts had been made to determinate the effect of an important number of diamagnetic or paramagnetic cations on the microstructure and magnetic properties of the hexagonal ferrites. Previous studies have reported a remarkable increase in the coercitive field of the hexaferrites of barium with the substitution partial of that by La, Lu, Sm, Nd and Gd. In the present research a structural and magnetic study of sintered permanent magnets with the general formula Sr 1-X Gd X/2 Na X/2 Fe 12 O 19 (0.00 ≤ X ≤ 0.10) was made. The samples were characterized by X-ray diffraction, vibrating sample magnetometry, scanning electron microscopy and elemental analysis (EDAX). The dependency of the densification, the medium grain size, the cells parameters and the magnetic properties with the gadolinium oxide content is discussed.