INTRINSIC AND MAGNET PROPERTIES OF La-Co SUBSTITUTED M-TYPE HEXAFERRITES

摘要

The effects of the La-Co substitution on both structural and magnetic properties of M-type hexaferrites are investigated by Moessbauer Spectrometry, X-Ray diffraction and magnetic measurements. Significant improvements are obtained in hard ferrite magnets with the Sr_(1-x)La_xFe_(12-y)Co_yO_(19) composition. These improvements stem from both the increase of the intrinsic magnetic properties of the modified M-type phase (observed with a simultaneous increase of x and y) and the optimization of the microstructure (through the use of fine powders and the optimization of the chemical composition). The optimum composition is based on a higher La content than Co content (y/x = 0.75), at the benefit of both lower irreversible losses and lower composition cost.