Fabrication and electromagnetic wave absorption properties of Fe_{<italic>x</italic>}O_{<italic>y</italic>}/BaTiO₃/C composites from red mud

To achieve the resource utilization of red mud, this work prepares FexOy/BaTiO3/C composite microwave absorbing materials using red mud as the iron source and soluble starch as the carbon source, employing sol-gel and solid-state reaction methods. First, a BaTiO3 precursor sol is obtained through the sol-gel process using titanium butoxide and barium acetate, which is then mixed uniformly with red mud and soluble starch. During the solid-state reaction, Fe2O3 in the red mud undergoes in situ carbothermic reduction to form Fe3O4 and Fe, which are evenly distributed within the composite, and the BaTiO3 exhibits a needle-like morphology. Experimental results show that by adjusting the solid-state reaction temperature and the raw material ratio, the phase composition, microstructure, and microwave absorption performance of the composites can be optimized. When the temperature is 700 ℃, RmBTS-700-1.2 exhibits a minimum reflection loss of −16.0 dB at a coating thickness of 2.0 mm, with an effective absorption bandwidth of 3.0 GHz. Meanwhile, RmBTS-700-1.8 achieves a minimum reflection loss of −32.6 dB at 10.7 GHz under the same coating thickness. The FexOy/BaTiO3/C composite microwave absorbing materials prepared in this study exhibit both strong dielectric loss and magnetic loss capabilities, providing a new approach for the comprehensive utilization of red mud and contributing to the realization of the carbon neutrality and carbon peak goals.