Ferromagnetic resonance and microwave behavior of ASn-substituted (A=Ni-Co-Zn) BaM-hexaferrites

ASn-substituted BaM-hexaferrites with compositions Ba[Fe.sub.12-2x][A.sub.x][Sn.sub.x][O.sub.19], where A = Co, Ni, Zn, and x = 0.5-2, were synthesized using a solid-state reaction at 1100-1300 [degrees]C. Hexaferrites formation was controlled by X-ray powder diffraction. The static magnetic properties were determined and the ferromagnetic resonance frequency of the powders was obtained using a vector network analyzer and a coplanar waveguide. It is shown that the degree of substitution (x) has a strong influence both on the static magnetic and the microwave behavior of the ceramics. Due to the changes in the anisotropy and saturation magnetization, the ferromagnetic resonance frequency shows a considerable decrease, from the 48 GHz for pure Ba[Fe.sub.12][O.sub.19], to about 10-20 GHz for samples with x [approximately equal to] 0.5, 1. Index Terms--Ferromagnetic resonance, hard ferrites, microwave filters.