** Department of Materials Science and Engineering, University of California, Los Angeles, CA 90025, USA) Preparation of Magnetopulmbite Type Ferrite

** Department of Materials Science and Engineering, University of California, Los Angeles, CA 90025, USA) Preparation of Magnetopulmbite Type Ferrite Thin Films by Dip-Coating Method and Magnetic Properties Toshio TSUCHIYA, Kazuhide YAMASHIRO* and J. D. MACKENZIE** ( Department of Materials Science and Engineering, Faculty of Industrial Science and Technology, Science University of Tokyo, 2641, Yamasaki, Noda-shi, Chiba 278 * Department of Chemical Industry, Faculty of Science and Technology, Science University of Tokyo, 2641, Yamasaki, Noda-shi, Chiba 278 ** Department of Materials Science and Engineering, University of California, Los Angeles, CA 90025, USA) Thins film of magnetoplumbite type ferrite (MFe12O19, M=Ba, Sr) have been prepared by the dip-coating method from sol gel process. Ferric nitrates, other metal nitrate and titaniumoxiacetylacetonate were used as law materials, and glycerol was used as solvent. A film was prepared by dipping a silica glass plate. The magnetoplumbite type ferrite was obtained by heat treatment at 750 Ž for 5h in air. The film thickness was about 0.08ƒÊm. The coercive forces (Hc) of the film and powder with the composition of 15BaO E85Fe2O2 was 3300 and 3050 Oe by heat treatment at 850 Ž for 48h respectively. These films were shown to have much larger Hc than the powder. The effect of substitution of titanium and cobalt ion in barium hexaf errite films and powders were investigated. The saturation magnetization of the powder in the system 15BaO E85 [ (100-2x) Fe2O3 ExTiO2 ExCoO) was almost constant in the range of 0 x 8.33. But the Hc changed drastically with increasing titanium and cobalt ion content. The Hc of the powder was controllable in the range of 50 Oe and 3050 Oe by changing the substitution contents for the same system. The Hc of the films was controllable in the range of 300 Oe and 3300 Oe for the same system. [Received March 24, 1989; Accepted June 23, 1989] Key-words: Barium hexaferrite, Thin film, Dip-coating, Coercive force, Saturation magnetization

Fig. 1. Film thickness versus number of dipping for Ba-ferrite films.

Fig. 3. X-ray diffraction patterns in the system of 15 BaO E85 Fe2O3 film (A) and 20 SrO E80 Fe2O3 film Fig. 2. X-ray diffraction patterns in the system of (B) heat-treated at 850 Ž for 48h. 15 BaO E85 Fe2O3 powder. Table 1. Magnetic properties of the films and pow der heat-treated at 850 Ž for 48h.

Table 2. Magnetic properties of the films heat-treated at 950 Ž for 48h. Fig. 4. Depth profiles of ESCA spectra in the system of 15 BaO E85 Fe2O3 film heat-treated at 850 Ž for 48h.

Fig. 5. X-ray diffraction patterns in the system of ybao E(100-y) [(100-2x) Fe203 ExTiO2 ExCoO] powder heat-treated at 850 Ž for 48h. Fig. 6. Substitution effect of Ti and Co on coercive force in the system of ybao E(100-y) [(100-2x) Fe2O3 ExTiO2 ExCoO] powder heat-treated at 850 Ž for 48h.

Fig. 7. Substitution effect of Ti and Co on saturation magnetization in the system of ybao E(100-y) [(100-2x) Fe2O3 ExTiO2 ExCoO] powder heat-treated at 850 Ž for 48h. Fig. 9. Substitution effect of Ti and Co on saturation magnetization in the system of ybao E(100y) [(100-2x) Fe2O3 ETiO2 ExCoO] films heat-treated at 850 Ž for 48h. Fig. 8. Substitution effect of Ti and Co on coercive force in the system of ybao E(100-y) [(100-2x) Fe2O3 ExTiO2 ExCoO] films heat-treated at 850 Ž for 48h. Fig. 10. Substitution effect of Ti-Co or Co on coer cive force for Ba (Sr) -ferrite films heat-treated at 850 Ž for 48h.

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