Wide microwave absorption bandwidth of the puffed-rice-based carbon obtained at 950 °C

Puffed-rice-based derived carbons are prepared by carbonizing precursor under 500 °C (S500) and 950 °C (S950). After X-ray diffraction and raman measurements, the S950 carbon shows sheet-like structure while swells with porous structure can be found in the S500 carbon, and the I D /I G value greatly increases from 0.87 of S500 to 1.06 of S950, indicating that more defects existing in the S950 carbon. The bandwidth for reflection loss (RL) below −10 dB of the S950 sample is enlarged to 10.3 GHz at matching thickness of 2.5 mm, however, nearly bandwidth lower 0.5 GHz can be found for the S500 carbon at the same condition. Moreover, the minimum RL value for S950 sample reaches −16.5 dB, better than that of −14.1 dB for S500 sample. Multiple reflection effects of the sheet and polarization loss caused by defect are the main factors for improving the microwave absorption performances of the S950 sample.