Mossbauer and magnetic study of substituted M- and W-type barium ferrite particles

A substituted barium ferrite of the M-type, BaFe/sub 10.48/Co/sub 0.76/Ti/sub 0.76/O/sub 19/ a modified W-type (about 1 W+0.3 S, where S is referred to as a spinel block), BaFe/sub 15.80/Co/sub 1.82/Ti/sub 0.5/Zn/sub 0.78/O/sub 28.3/, and a mixed type, BaFe/sub 12.6/Co/sub 0.7/Ti/sub 0.7/Ni/sub 0.36/Zn/sub 0.64/O/sub 23/ (about 0.5 M+0.5 W) were prepared using the coprecipitation salt catalysis technique. The structure of the samples was examined by X-ray diffraction and high-resolution electron microscopy. Magnetic measurements and Mossbauer spectra show that the sample of the modified W-type has the largest specific magnetization 70.2 emu/g and smallest coercivity, 660 Oe. Modified W-type barium ferrite has magnetic properties superior to the M-type; this improved material can be successfully made by increasing the number of S-blocks in the unit cell and by substituting Zn/sup 2+/ and Co/sup 2+/ ions for Fe/sup 2+/ at the tetrahedral f/sub IV/ site.<
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