Influence of heat treatment temperatures on structural and magnetic properties of Sr0.50Ca0.20La0.30Fe11.15Co0.25O19 hexagonal ferrites

M-type ferrite Sr0.50Ca0.20La0.30Fe11.15Co0.25O19 magnetic powders and magnets were prepared by a ceramic process. The phase identification of magnetic powders was performed by X-ray diffraction. At calcination temperatures ranging from 1170 to 1270 °C, the phase compositions of the magnetic powders consist of M-type hexaferrites together with small amount of impurity phases such as α-Fe2O3, LaFeO3 and CoFe2O4. At calcination temperatures above 1270 °C, single-phase M-type hexaferrites can be obtained. The microstructures of the magnets were investigated by field emission scanning electron microscopy. The particles appear in hexagonal plate-like shape and the particles are distributed homogeneously. The radial shrinkage of the magnets increases with the increase of calcination or sintering temperature. The magnetic properties of the magnets and magnetic powders were measured by a permanent magnetic measure equipment and a vibrating sample magnetometer, respectively. For high remanence, intrinsic coercivity, magnetic induction coercivity and maximum energy product, the optimized calcination and sintering temperatures are 1250 °C and 1190 °C, respectively.