Ultra-wide bandwidth and enhanced microwave absorption performance of rod/flake-shaped FeSiAl@TiO2 composites

Rational design of both microstructure and composition to achieve magnetic-dielectric synergy serves as an effective strategy for preparing high-performance microwave absorbing materials. This study reports the successful fabrication of rod/flake-shaped FeSiAl@TiO₂ composites via a simple approach combining ball milling and tetrabutyl titanate hydrolysis. The one-dimensional (rod) and two-dimensional (flake) morphologies of FeSiAl induce magnetic shape anisotropy, effectively overcoming the Snoek’s limit and boosting both permeability and magnetic loss at high frequencies. Concurrently, the semiconducting TiO₂ coating moderates the conductive network, reducing the real part of permittivity and achieving favorable impedance matching. Furthermore, abundant heterogeneous interfaces and defects such as oxygen vacancies generated within the composite substantially enhance interfacial and dipole polarization. The synergy between these tailored magnetic and dielectric loss mechanisms results in excellent microwave absorption performance, evidenced by a minimum reflection loss (RL min ) of −50.17 dB at a matching thickness of 1.9 mm and an ultra-wide effective absorption bandwidth of 8.18 GHz at a thickness of 2.0 mm. This work presents a promising strategy for developing high-performance magnetic-dielectric absorbers.