Preparation of Oriented Barium Hexaferrite Films by Electrophoretic Deposition

Stable, hard-magnetic suspensions were prepared from barium hexaferrite (BaHF) particles. The particles were stabilized in 1-butanol with the adsorption of dodecylbenzene sulphonic acid onto the particles' surfaces. This adsorption was observed in the FTIR spectra and resulted in a high zeta-potential of 110 mV. The stable suspensions were then used for electrophoretic deposition. The magnetically oriented films with a thickness of 15 mu m were prepared after sintering the deposits at different temperatures. The degree of orientation of the BaHF hexagonal plates in the films was examined with electron microscopy, X-ray diffraction (XRD), and magnetic measurements. Large differences between in-plane and out-of-plane magnetic properties of films were observed. The BaHF films exhibit a very high out-of-plane M(r)/M(s) ratio of 0.88, which confirms the high XRD degree of orientation of 94%.