Magnetic anisotropy of chemically coprecipitated Zn/sub 2/W ferrite

摘要

BaZn/sub 2/Fe/sub 16/O/sub 27/ is prepared by several modified coprecipitation methods and studied using differential thermal analysis, X-ray analysis, static magnetic measurements and ferromagnetic resonance absorption. At low annealing temperatures M- and W-type ferrite as well as monoferrite ZnFe/sub 2/O/sub 4/ crystallize depending on the coprecipitation method. In powders annealed below 1100/spl deg/C single-domain hexaferrite phase with uniaxial anisotropy comparable to Zn/sub 2/W ferrite mainly effects the microwave absorption loss. Ferromagnetic resonance is used to determine an effective anisotropy field strength of H'/sub A/=2K'/sub 1///spl mu//sub 0/M/sub S/ equal to 979 kA/m and K/sub 2//K'/sub 1/=-0.03 leading to K/sub 2/=-7.9 kJ/m/sup 3/ for these powders.