Microwave absorption properties of SrxBa3-xCo2Fe24O41 hexaferrites in the range of 0.1-18 GHz

SrxBa3-xCo2Fe24O41 Z-type hexaferrites have been prepared by the citric acid sol-gel method, and the structural and electromagnetic properties have been investigated in detail. The results showed that single-phase Z-type hexaferrites were observed, and all samples exhibited excellent soft magnetic properties. For the sample with x = 1.5, a high resonant frequency fr = 3.50 GHz and initial permeability μ′ = 2.76 at 100 MHz was obtained. The calculated frequency dependence spectrum of the reflection loss (RL) showed a largest absorbing value of −48.5 dB at 17.6 GHz with a thickness of 5.0 mm. With the increasing thickness t, two local minimum RL values were observed from the RL-t curve. One was −43.6 dB at t = 4.3 mm and the other was −45.8 dB at t = 2.8 mm. The dependence of percentage bandwidth WP on thickness t was studied. As t increasing, WP increased firstly and then slowly decreased, reaching the maximum value of 96.1% at t = 3.3 mm.