Abating dopant competition between dual high-valence ions in single-phased barium ferrite towards ultra-broad microwave absorption

Abstract

Microwave absorbers with ultra-broad bandwidths are extremely effective in combating the wide range of electromagnetic pollution and radar detection. However, the conventional magnetoelectric compositing techniques for achieving a wide absorption bandwidth suffer from drawbacks of a complex preparation process and low yield production. A single-phased microwave absorber is an ideal choice for large-scale application while integrating desired levels of dielectric loss and a broad magnetic loss continues to pose a significant challenge. In this work, an ultra-broad single-phase microwave absorber is developed by abating the doping competition of dual high-valence Zr⁴⁺ and Ti⁴⁺ ions in the M-type barium ferrite. Due to the disparities in electronegativity and ionic radii of Zr⁴⁺ and Ti⁴⁺ ions, enhanced incorporation of high-valence ions substituting for Fe³⁺ ions in Zr⁴⁺–Ti⁴⁺ ion co-doped systems to simultaneously improve the complex permittivity and generate multi-resonance permeability. First-principles calculations and magnetic resonance peak-differentiating and imitating results show that the enhanced electromagnetic properties stem from the optimized electronic structure and strengthened exchange coupling effect. By optimizing the dopant Zr⁴⁺ and Ti⁴⁺ contents in terms of composition of BaFe_12−2xZr_xTi_xO₁₉ with x = 0.4, an ultra-broad bandwidth of 16.3+ GHz and an ultra-strong absorption intensity of up to −54.8 dB have been successfully achieved at a very thin matching thickness down to ∼1.08 mm, much superior to those of the existing various types of state-of-the-art microwave absorbers. Therefore, this material shows great application potentials as preeminent microwave absorbers with unprecedented comprehensive performance.