Compositional dependence of tbe electromagnetic wave absorption properties of BaFe12-x-yTixMnyO19 in the GHz frequency range

The compositional dependence of the electromagnetic wave absorption properties of Barium M-type ferrite, in which a mixture of Ti and Mn were substituted for Fe, was investigated. Single phase M-type structure was obtained for the BaF12-x-yTixMnyO19 sintered samples with compositions x<2.5 and y<2.5, and Mn substitution allowed the single phase to form at higher Ti contents. It was found that the natural resonance frequencies (f(r)) of these sintered samples can be controlled in the range 3.85 to 60.18 GHz, by changing the Ti and Mn content. Almost all of the samples in the M-type single phase region impedance-matched and exhibited a minimum reflection loss (R.L.) less than -20 dB at matching frequencies (f(m)), with matching thicknesses (d(m)) smaller than 4 mm, which demonstrates that these ferrites can function as thin electromagnetic wave absorbers in this frequency range. Some samples outside this single phase region with a high Mn and Ti content also impedance-matched, however the impedance matching is more sensitive to changes in Ti content than in Mn content. As a result, f(m), and d(m) values varied from 33.25 to 3.75 GHz and from 0.27 to 3.80 mm, respectively.