Effect of CaO and SiO/sub 2/ additives on magnetic properties of SrZn/sub 2/-W type hexagonal ferrite

An experiment was carried out to investigate the effect of CaO and SiO/sub 2/ additives on the magnetic and physical properties of Sr-Zn W-type hexagonal ferrite. The specimens were prepared by the conventional manufacturing method without atmosphere control. It was found that the magnetic properties of SrO/spl middot/2ZnO/spl middot/8Fe/sub 2/O/sub 3/ are considerably improved on adding 1 wt% CaO and SiO/sub 2/ together. The optimum condition of making magnets with suitable properties are as follows: chemical analysis composition: Sr/sub 0.844//sup 2+/Zn/sub 2.269//sup 2+/Fe/sub 2.269//sup 2+/Fe/sub 1.80//sup 2+/Fe/sub 14.844//sup 3+/Ca/sub 0.161//sup 2+/Si/sub 0.140//sup 4+/O/sub 27/; semisintering condition: 1275/spl deg/C/spl times/1 h in air; sintering condition: 1225/spl deg/C/spl times/0.5 h in air. The magnetic properties are J/sub m/=0.438 T, J/sub r/=0.402 T, H/sub c/J=92.4 kA/m, H/sub c/B=88.8 kA/m, (BH)/sub max/=20.3 kJ/m/sup 3/, T/sub c/=393/spl deg/C, H/sub A/=968 kA/m, K/sub A/=2.11/spl times/10/sup 5/ J/m/sup 3/, and n/sub B/=32.8 /spl mu//sub B/.<
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