Ferroelectrically induced dual band microwave absorption in multiferroic BiFeO<inf>3</inf>/acrylo-nitrile butadiene rubber composites

Nanostructured multiferroic BiFeO3 powder has been synthesized using sol–gel route followed by optimized post-annealing treatment. The phase pure rhombohedral structure of prepared powder was confirmed by X-ray diffraction and Fourier transform infrared studies. The room temperature weak ferromagnetic nature (~ 0.15 emu/g) exhibited by the nanocrystalline BiFeO3 sample (~ 50 nm) is attributed to the canted spin ordering in the sample. The BiFeO3/NBR rubber composites, with 50–80 wt% filler loading fractions, show the dual band resonating microwave (MW) absorption behavior. The reflection loss (R.L.) values enhanced and required absorber thickness reduced simultaneously with increasing BiFeO3 loading fraction in composite samples. These results confirm that the ferroelectric properties of multiferroic BiFeO3 are contributing significantly for the observed MW absorption with respect to the magnetic contribution.