Enhanced microwave absorption of multiferroic Co2Z hexaferrite–BaTiO3 composites with tunable impedance matching

• We proposed a new microwave absorber based on multiferroic composites.
• The microwave magneto-dielectric behaviors depend on the mass ratios of Co2Z/BT.
• The impedance matching could be manipulated by modifying phase fraction of BT.
• The optimal reflection loss was tuned over a wide frequency range.
• An improved absorption performance was achieved by means of Co2Z–BT composites.

The microwave absorbing properties of multiferroic particulate composites consisting of Co2Z hexaferrite and BaTiO3 (BT) were investigated over a frequency range of 2–18 GHz. The effective complex permeability and permittivity of Co2Z–BT composites are shown to be effectively manipulated by varying the weight ratio of the two phases, which consequently demonstrates a strong tunability in the optimal working frequency and minimum reflection loss (RL). For the optimal Co2Z–10BT composite, the RL peak at a thickness of 2.0 mm was enhanced by 97.8% in comparison with that of the single phase Co2Z hexaferrite. Moreover, the impedance-matched RL characteristics below 10 GHz show a substantial improvement in both thickness and bandwidth with increasing BT content. This work clearly shows the potential to tune the impedance matching and microwave absorption performances of multiferroic composites.