Microwave electromagnetic and absorbing properties of Dy³⁺ doped MnZn ferrites

Dy³⁺ doped Mn-Zn ferrites Mn_0.3Zn_0.7Fe_2-xDy_xO₄x=0, 0.01, 0.02, 0.03, 0.04were prepared by the conventional solid-state reaction. The crystal structure, surface morphology and electromagnetic properties of the calcined samples were characterized by X-ray diffraction analysis(XRD), scanning electron microscopy(SEM) and network analyzer (Agilent 8722ET). All the XRD patterns showed the single phase of the spinel-type ferrite without other intermediate when x≤0.03. The average crystallite size was about 44-56 nm. The microwave electromagnetic properties of the samples were studied at the frequency range from 2 GHz to 18 GHz. It was shown that small amounts of Dy³⁺ substitution could adjust microwave electromagnetic parameters magically. The tan δ exhibited a maximal peak when x=0.03, and the peak value was 0.56. It indicated that the microwave electromagnetic loss properties were excellent when x=0.03. Furthermore, the reasons were also discussed using electromagnetic theory. The reflection loss (RL) increased with the Dy³⁺ content when x<0.04. The Mn_0.3Zn_0.7Fe_1.97Dy_0.03O₄ ferrite displayed excellent microwave absorption properties. The frequency (with respect to -10 dB) started from 11.9 GHz, and the bandwidth reached about 3.5 GHz. The peak value of RL was about -20.5 dB at a matching thickness of 2.7 mm.