Using Edta Of Barium Ferrite Thin Films Prepared By Sol - Gel And Powder

Barium hexaferrites (BaFe12O19, BaM) with magnetoplumbite structures are traditional permanent magnetic materials. Due to its high magnetocrystalline anisotropy field, proper saturation magnetization coercivity force and magnetic energy product, as well as excellent chemical stability and mechanical strength, BaM was regarded as one of the potential materials for ultra-high density perpendicular recording media. Meanwhile, its intrinsic high anisotropy, narrow magnetic anisotropy field distribution, and large resistivity enable it to be applied in microwave communication. In this paper, barium ferrite thin films and powders were prepared by sol-gel method with ethylene-diamine-tetra-acetic acid (EDTA) as chelating agent.The paper mainly researched the influence of the amount of EDTA and the PH value of the precursor as well as the ratio of Fe3+to Ba2+on the texture, morphology and the magnetic properties of the thin films. The results indicate that when the ratio of Fe3+to Ba2+was8:1, the pure BaM thin films with hexagonal platelet-shaped grains were fabricated and the films had preferred c-axis orientation perpendicular to the substrate plane. While the ratio of Fe3+to Ba2+was higher than8:1, the pure BaM thin films were not formed. The amount of EDTA had a direct effect on the morphology of the film, especially when the EDTA was insufficient there were many dot grains in the film due to too much free metal ions in the precursor. When the mole ratio of EDTA to all metal ions was1:1and the PH value was7, the film with the best texture and morphology was obtained. However, the PH value almost had no influence on the morphology of the films. The films with pure BaM prepared showed dramatically anisotropy. The highest saturation magnetization of240emu/cc and the maximum coercivity force of270Oe out of plane direction were achieved at room temperature. The epitaxial relationships between the film and the substrate were [001]sapphire|[001]BaMand [110]sapphire‖[100]BaM?The nano-sized hexagonal barium ferrite powders were prepared when the precursor was calcined at1000℃for4hours. The BaFe12O19with the least impurity phase was formed when the ratio of Fe3+to Ba2+was8:1, while the higher ratio there was Fe2O3in the powders, which was as the same as the thin films fabricated. However, the saturation magnetization and coercivity force of the mixed barium ferrite particles were higher due to the existence of exchange coupling. Sb-doped nano-sized barium ferrite powders were prepared. The investigation showed that as the number of antimony (Sb) atoms increasing, the composition of the particle was becoming more and more complex, the hexagonal platelet-shaped grains decreasing, the saturation magnetization and remanence smaller, which were consistent with the theory. While the doped particles were compressed into bulk, the saturation magnetization and remanence showed the same change like powders, but the coercivity forces increasing.