Preparation and Characterization of Al-Substituted M-Type Ferrites by Sol-Gel Auto Combustion Method

Abstract

M-type ferrites especially barium and strontium ferrite has dominant position in permanent magnet market due to its high coercivity, moderation saturation magnetization and energy product. Apart from its application in permanent magnets, there are also useful for highs frequency application due to it high anisotropic constant and ferromagnetic resonance frequency. In the present work, BaFe12-xAlxO19 and SrFe12-xAlxO19 (x=0, 1, 2) sintered magnets have been prepared. The Al-substituted powders were prepared by sol-gel auto-combustion method. The structural, microstructural and magnetic properties of the powders and sintered magnets were measured by X-Ray diffraction, scanning electron microscopy, and Vibrating Sample Magnetometer respectively. It is found the Al substitution remarkably effect its magnetic properties. A very high coercivity of 10.70KOe were observed in Al substituted sintered magnets. However, saturation magnetization found to decrease with the substitution. These high coercivity magnets could be useful for permanent magnet application where large demagnetization fields are dominating.