Effect of Zn substitution on the electromagnetic and microwave absorbing properties of BaCo2 hexaferrite

A series of Zn doped BaZnxCo2-xFe16O27 (x = 0, 0.3, 0.5, 0.7, 0.9, 1.2) W-type hexaferrites were successfully synthesized via chemical co-precipitation method. The XRD result showed that the structure of W-type hexaferrite has not been affected by the substitution of Zn. The morphology of the particles measured from SEM was the flat hexagonal sheet with large size about 15 mu m and high aspect ratio of similar to 20. And the complex permittivity and permeability of BaZnxCo2-xFe16O27 which were determined by microwave vector network analyzer in the frequency of 1-18 GHZ was calculated based on the measured data. For the sample with x = 0.7, the minimum reflection loss of -52.8 dB was obtained at 12.8 GHz and the effective absorbing bandwidth reached 4.5 GHz for the sample with the thickness of 2.1 mm. At the thickness of 2.5 and 3.0 mm, the minimum reflection loss were -14.7 dB at 10.35 GHz and -13.2 dB at 8.1 GHz and the effective absorbing bandwidth were 4.93 and 2.21 GHz, respectively.