MAGNETIC-PROPERTIES OF BA-FERRITE POWDERS PREPARED BY SURFACTANT ASSISTED BALL-MILLING

Magnetic properties of Ba-ferrite powders processed by a novel method: surfactant assisted low energy ball milling, are discussed. By using cationic and anionic surfactants at pH values above and below the poin t of zero charge of the oxide surface, some remarkable changes in magn etic properties of the milled material are produced. Vibrating sample magnetometry (VSM) and ferromagnetic resonance are applied for sample evaluation. Directly after milling the particles are in the submicron range with a narrow size distribution. By application of an annealing procedure in air or vacuum to prepared powders changes were observed. Final annealing in air of the samples annealed first in vacuum produce s Ba-ferrite powder with m(o)M(s) and H(c) values in a remarkably broa d range 0.457-0.564 T, and 136-195 kA/m respectively.