Dual Band Resonance in Tetragonal BaTiO3/NBR Composites for Microwave Absorption Applications

Tetragonal BaTiO3 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 2O similar to 45 degrees and 310, 520, and 720 cm(-1) characteristic vibrational modes in Raman spectroscopic measurements confirm the tetragonal crystallographic structure of BaTIO3 bulk samples. The 1100 degrees C annealed BaTiO3 sample showed optimal tetragonality similar to 1.016 and the same is used for BaTiO3-acrylonitrile butadiene rubber (NBR) composites at different BaTiO3 loading fractions in parts per hundred (PHR). These BaTiO3/NBR composite systems exhibit dual band microwave resonance, widening the operating window for microwave absorption applications. Eighty PHR BaTiO3/NBR composite exhibits microwave reflection losses (RL) at 9.5 and 16.5 GHz with similar to-9 and similar to-18 dB reflection losses, respectively. The onset of dual band is attributed to the ferroelectric-induced dipolar relaxation at 9.5 GHz and its second-order resonance at 16.5 GHz in such composite systems.