Improvement of soft magnetic properties on hexagonal ferrites

The substitution of elements was carried out to improve the soft magnetic properties in hexagonal ferrites. A series of Ba3Co2R 2Fe24-xO41 samples (R = La, Nd, Gd, Dy, Ho, Yb) with Z-type structure were made. The initial permeability of Gd 3+-substituted sample (x = 0.1) was the highest of all samples, because the apparent specific anisotropy field of the sample was the lowest. The substituted sample Ba3Co2Mn0.5xTi 0.5xFe24-xO41 with x=0.4 had the maximum μ′ of 25.7 and μ′ ′ × fr product of 17.6 GHz. The M-Tcurve showed an anomalous drop below the Curie temperature, which reflected the change from in-plane magnetic anisotropy to vertical one with increasing temperature. BaCoxTixFe 12-2xO19 (x=1-3) were prepared. The initial permeability increased to 27 for a sample with x= 1.15. The reason for this may be that the coercivity becomes small as a result of the decrease in the anisotropic magnetic field. SrCo2+,Me4+yFe12-2yO 19 (Me = Zr, HO samples were also fabricated. For SrCo yZryFe12-2yO19 (y=0-1.2), magnetization increased slightly for the sample of y=0.4, and then decreased with increasing y. Coercivity drastically decreased up to y = 1.2. Magnetic behavior of the Co-Hf substituted sample was similar to that of the Co-Zr substituted one.