Exchange coupling in SrFe12O19/CoFe2O4 composites: Effect of component proportions

Abstract

(100-x)SrFe12O19/(x)CoFe2O4 composites were prepared by ball milling technique using different fractions of hexagonal and cubic ferrite powders as precursors, namely x = 10, 20, 30, 40 wt%. After grinding in a ball mill, as-prepared composites were annealed at 900 °C for 3 h. X-ray powder diffraction was carried out for structural analysis. Energy dispersive X-ray analysis allowed elemental analysis of the composites. Magnetic properties were studied at room temperature by magnetization versus applied external magnetic field, direct current demagnetization and isothermal remanence magnetization measurements. A relationship has been established between structural parameters (depending on the proportions of fractions of different crystallite size) and magnetic properties of the composites. Composite sample with 10 wt% CoFe2O4 reveals the highest energy product (BH)max = 10.9 kJ/m3, which is approximately 20 % higher than that of pristine SrFe12O19. The presence of the exchange coupling effect extracted from Henkel plots nicely explain the improved magnetic characteristics of composite.