Abstract: In light of increasingly complex electromagnetic (EM) environments and growing multi-spectrum detection threats, the development of high-performance stealth materials has become critically urgent. Although oxygen-deficient Ti₄O₇ exhibits relatively high electrical conductivity and EM attenuation capability, its excessively high dielectric constant often leads to impedance mismatch, thereby limiting its practical applicability. To address this challenge, Ti₄O₇ can be integrated with magnetic or dielectric materials possessing complementary EM properties, enabling enhanced ferromagnetic resonance and dielectric loss performance. In this study, the electronic structure and crystal defects of TiO₂ were initially modulated via a hydrogen reduction method, successfully yielding phase-pure Ti₄O₇. Subsequently, a magnetic CoNi alloy and carbon nanotube (CNT) were deposited onto its surface through a solvothermal process, forming a Ti₄O₇/CoNi/CNT composite absorber. Within this architecture, the CoNi layer contributes to enhanced interfacial polarization and magnetic loss, while the incorporation of CNT effectively increases conductive loss and reduces overall material density, thus achieving a synergistic improvement in both dielectric and magnetic loss mechanisms. Experimental results demonstrate that when the Ti₄O₇/CoNi/CNT composite with a CNT mass fraction of 4% is incorporated into a paraffin matrix at a loading content of 45% (in mass) and a thickness of 2.03 mm, the minimum reflection loss reaches -80.6 dB, with an effective absorption bandwidth of 2.0 GHz. In conclusion, the Ti₄O₇/CoNi/CNT composite exhibits exceptional EM wave absorption performance, offering significant implications for the stealth protection of advanced platforms such as unmanned aerial vehicles.

Key words: Ti₄O₇, oxygen defect, dielectric loss, impedance matching, microwave absorption