Electromagnetic and microwave absorbing properties of W-type barium ferrite doped with Gd3+

Abstract

W-type barium ferrites doped with Gd(superscript 3+), Ba(subscript 1-x)Gd(subscript x)(Zn0.3Co0.7)2Fe16O27 (x=0, 0.05, 0.10, 0.15, 0.20), were prepared by a sol-gel method. The effects of Gd(superscript 3+) substitution on their microstructure, electromagnetic properties and microwave absorptive behavior were analyzed. The XRD patterns showed the single phase of W-type barium ferrite when x≤0.15. Microwave electromagnetic properties of samples were studied at the frequency range from 2 GHz to 18 GHz using a network analyzer (Agilent 8722ET). The complex permittivity e(e', e”) increased gradually when x≤0.10, but it decreased as x=0.15. The real permeability (μ') decreased with the increase of Gd(superscript 3+) content, while the imaginary permeability (μ”) increased when x≤0.10. All these reasons were discussed using the electromagnetic theory. Furthermore, the ferrite-epoxy compound coating materials with 80 wt.% of Ba0.9Gd0.1(Zn0.3Co0.7)2Fe16O27 were prepared to measure the microwave absorbing properties. The maximum of reflection loss (RL) reached about -27 dB and RL was below-10 dB in the frequency range of 8-18 GHz when the thickness was 1.92 mm.