Ultra-wideband microwave absorption of W-type/spinel composite ferrites based on the distributions of Co2+ and Zn2+

We successfully synthesized W-type/Spinel composite ferrites containing Co and Zn ions (W/ x S ( x  = 0.5, 1, 2, 4, 8)) via “one-pot” sol-gel auto-combustion method. By setting up the comparison groups, the enhanced absorption performance of the composite ferrite materials compared with the single-phase material is clearly demonstrated. The “one pot” synthesis makes the co-existence of Co 2+ and Zn 2+ in the W-phase and S-phase lattices, resulting in composite ferrites with excellent soft magnetic and microwave absorption properties. SEM-EDS characterization revealed that Co and Zn were roughly evenly distributed in the W and S phase. Benefitting from the increased saturation magnetization and decreased magnetocrystalline anisotropy caused by Zn substitution, composite ferrites with excellent soft magnetic properties were obtained at appropriate Co/Zn ratios. W-type/Spinel composite ferrites exhibit tunable magnetic loss characteristics via changing the total Co/Zn molar ratios. On account of the broadband high magnetic loss characteristics, the well comprehensive microwave absorption properties were obtained. For W/0.5S, a minimum reflection loss of −70.46 dB (d = 1.76 mm) is obtained. For W/2S, a maximum effective absorption bandwidth of 10.67 GHz (d = 2.15 mm) is obtained. This work will provide new ideas for improving the microwave absorption performance of existing ferrite materials.