• • Fe-N4 single-atom coordination in SiOC ceramic fibers achieves efficient low-frequency absorption (C-band, 4–8 GHz) while maintaining stability above 500°C, overcoming the traditional trade-off between magnetic loss and thermal stability.
• • EXAFS analysis confirms exclusive Fe-N peak at ~1.5 Å and no Fe-Fe peak at ~2.2 Å, proving complete atomic dispersion without Fe clusters, which is critical for preventing agglomeration-induced performance degradation.
• • The nitrogen-induced 'nano-to-atomic' transformation mechanism, driven by reactive nitrogen species attacking α-Fe nanoparticles (15–25 nm), enables complete conversion to Fe-N4 sites at a critical nitrogen doping threshold, ensuring uniform active sites.
• • The material retains magnetic element contribution to low-frequency response without oxidation issues, as Fe atoms are stabilized by strong Fe-N covalent bonds, offering a scalable route for high-temperature electromagnetic wave absorbers.