The microwave magnetic performance of Sm3+ doped BaCo2Fe16O27

W-type barium hexaferrites doped with Sm3+, Ba1-xSmxCo2Fe16O27 (x = 0.0, 0.05, 0.1, 0.15, 0.2) were prepared by the conventional solid-state reaction. The structure and electromagnetic properties of the calcined samples were studied using powder X-ray diffraction (XRD) and network analyzer (Agilent 8722ET). All the XRD patterns showed the single phase of the magnetoplumbite barium ferrite without other intermediate phase when x <= 0.15. The microwave electromagnetic properties of the samples have been studied at the frequency range from 2 GHz to 18 GHz. It was shown that epsilon' and epsilon '' increased slightly, and the maximum of epsilon '' shifted to low frequency position with Sm3+ ions doping. The mu '' and mu' values were improved significantly when x = 0.15, and the peak value of mu '' was about 1.6 at 7 GHz and 1.75 at 18 GHz position, respectively, exhibiting excellent microwave magnetic performance. Furthermore, the reasons have also been discussed using electromagnetic theory. Ba0.85Sm0.15Co2Fe16O27 powders (85% by weight) were mixed with epoxy resin to form compound coating materials with different thicknesses, the reflection loss values of which were also measured. It is shown that the reflection loss value increases with the increase of the coating thickness under our experimental range. The maximum of reflection loss reached about -23 dB and it was below -10 dB at the frequency range from 8 GHz to 18 GHz, when the thickness was 1.8 mm. (C) 2009 Published by Elsevier B.V.