Sr系W型フェライトの磁気特性に及ぼすステアリン酸Ba添加の影響

概要

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An experiment was carried out to investigate the effect of Ba-Stearate as a reducing agent on the magnetic and physical properties of SrFe2-W type hexagonal ferrite. It was found that the magnetic properties of SrO · 8.5Fe2O3 were improved by adding 0.3 wt% of Ba-Stearate, 0.3 wt% of SiO2, and 1.25 wt% of CaCO3 together. The optimum conditions for making magnets were as follows. Composition: SrO · 8.5Fe2O3 added with 0.3 wt% of Ba-Stearate, 0.3 wt% of SiO2, and 1.25 wt% of CaCO3. Semisintering condition: 1350°C×4.0 h in nitrogen gas atmosphere, Drying condition: 180°C×2.5 h in air, Sintering condition: 1160°C×1.5 h in nitrogen gas atmosphere. Magnetic and physical properties of a typical sample were Jm=0.48 (T), Jr=0.44 (T), HcJ=191.9 (kA/m), HcB=187.5 (kA/m), (BH)max=32.9 (kJ/m3), Tc=489 (°C), HA=1350 (kA/m), KA=3.10 (×105 J/m3). The lattice constants of this compound were a=5.896 (×10-10 m), c=32.77 (×10-10 m), and c/a=5.558.