Superfluous low-frequency microwave radiation becomes a serious problem gradually at current age, herein, the Sn-Fe-O multiphase compounds were combined with novel biochar by using Salvia miltiorrhiza Bunge's leaves as carbon source, which can realize the recycling of this useless Chinese medicinal waste for economy. Also, the influence of preparation process on the final components, structures and properties in composites have been evaluated, the P2 composite possesses the optimal electromagnetic absorbing property i.e. the maximum reflection loss achieves −45.09 dB at 0.48 GHz with efficient absorbing bandwidth of 0.14–1.16 GHz at the matching thickness of 2 mm, moreover, a broad efficient absorbing bandwidth of 0.86–3 GHz can obtained for only 0.71 mm as well. The outstanding absorption of this sample can be ascribed to the synergistic effect of multiple low-frequency absorption mechanisms such as nature resonance, eddy current, conduction and electron hopping, multi-ply interfacial polarization etc., suggesting its superiority for being applied as a new-type low frequency electromagnetic wave absorber for practical use.

多余的低频微波辐射在当今时代逐渐成为一个严重的问题，在此，利用丹参将Sn-Fe-O多相化合物与新型生物炭结合邦吉的叶子作为碳源，可以实现这种无用的中药废弃物的经济回收利用。此外，还评估了制备工艺对复合材料最终成分、结构和性能的影响，P2 复合材料具有最佳的电磁吸收性能，即在 0.48 GHz 时最大反射损耗达到 -45.09 dB，有效吸收带宽为 0.14-1.16 GHz 在匹配厚度为 2 mm 时，此外，仅 0.71 mm 也可以获得 0.86-3 GHz 的宽有效吸收带宽。该样品的出色吸收可归因于自然共振、涡流、传导和电子跳跃、多层界面极化等多种低频吸收机制的协同作用，