Dual Band Resonance in Tetragonal BaTiO 3 / NBR Composites for Microwave Absorption Applications

Tetragonal BaTiO 3 bulk samples are prepared using the solid‐state route in conjunction with intermediate high‐temperature annealing steps. The (002) and (200) X‐ray diffraction peaks near 2Ɵ~45° and 310, 520, and 720 cm −1 characteristic vibrational modes in Raman spectroscopic measurements confirm the tetragonal crystallographic structure of Ba TIO 3 bulk samples. The 1100°C annealed BaTiO 3 sample showed optimal tetragonality ~1.016 and the same is used for BaTiO 3 –acrylonitrile butadiene rubber ( NBR ) composites at different BaTiO 3 loading fractions in parts per hundred ( PHR ). These BaTiO 3 / NBR composite systems exhibit dual band microwave resonance, widening the operating window for microwave absorption applications. Eighty PHR BaTiO 3 / NBR composite exhibits microwave reflection losses ( RL ) at 9.5 and 16.5 GH z with ~−9 and ~−18 dB reflection losses, respectively. The onset of dual band is attributed to the ferroelectric‐induced dipolar relaxation at 9.5 GH z and its second‐order resonance at 16.5 GH z in such composite systems.