SURFACTANT-ASSISTED BALL-MILLING OF BAFE12O19 FERRITE DISPERSION

A systematic study of the influence during mechanical processing of el ectrostatic interactions involving cationic and anionic surfactants on the surface and bulk properties of the complex oxide system barium fe rrite is reported. Morphological examination by scanning electron micr oscopy shows a rapid decrease in powder particle size and homogenisati on with milling time. In addition, from X-ray diffraction experiments changes in the crystal structure of the oxide were found. Barium ferri te decomposition (oxide phases separation) was linked with surfactant molecule type (ion and counterion) and oxide surface electrostatic pot ential. During room-temperature ball milling in aqueous dispersions a process of fast decomposition can be observed. For a cationic surfacta nt at pH 10 the milling terminates in BaCO3 and magnetite Fe3O4 as mai n phases and the material remains magnetic. In the case of anionic sur factant type and the same pH value, the barium ferrite structure remai ns as the main phase, because surfactants do not absorb onto the oxide surface. On the basis;of adsorption driven by electrostatic interacti ons it was possible to explain the effects of different surfactants on the milling product in dispersions with a low pH value.