1999 Volume 23 Issue 1_2 Pages 611-613
The effect of substitutional elements (Ti, Sc, Zr, Ti0.5M0.5, Zr0.5M0.5, Sn0.5M0.5 (where M = Co, Ni, Zn, Mn, Mg, Cu)) on the natural resonance frequency of Barium M-type hexagonal ferrite (BaFe12O19) was investigated, with the aim of finding a material suitable for use as a microwave absorber in the GHz range. It was found that the anisotropy field (HA) decreases with increasing amounts of substitutional element, which leads to the natural resonance frequency (fr) and the matching frequency (fm) shifting to lower values. Some Ti0.5M0.5 substituted samples exhibited values of fr within the 1 to 20 GHz range, and the minimum reflection loss (R. L. ) for these samples was found to be less than -20dB. In particular, because of their large values of magnetic loss ((μ") =4.6 and μ" =4.0), the BaFe9(Ti0.5Mn0.5)3O19 and BaFe9.5(Ti0.5Mn0.5)2.5O19 samples had small matching thicknesses (dm) of 0.58mm and 0.53mm, with matching frequencies (fm) of 12.35GHz and 15.75GHz, respectively. Therefore, it may be concluded that Barium M-type ferrite is a candidate for use as a microwave absorber in the GHz range.
