High-performance microwave absorption by optimizing hydrothermal synthesis of BaFe 12 O 19 @MnO 2 core-shell composites.

Stealth technology advances in radar-absorbing materials (RAMs) continue to grow rapidly. Barium hexaferrite is the best candidate for RAMs applications. Manganese dioxide (MnO 2 ) is a transition metal with high dielectric loss and can be used as a booster for changing polarization and reducing reflection loss. The advantages of BaFe 12 O 19 and MnO 2 can be combined in a core-shell BaFe 12 O 19 @MnO 2 composite to improve the material's performance. MnO 2 composition, temperature, hydrothermal holding time, and sample thickness all have an impact on the core-shell structure. In this study, a core-shell BaFe 12 O 19 @MnO 2 composite is synthesized in two stages: molten salt synthesis to produce BaFe 12 O 19 as the core and hydrothermal synthesis to synthesize MnO 2 as the shell. In the hydrothermal synthesis, BaFe 12 O 19 and KMnO 4 were mixed in deionized water using different mass ratios of BaFe 12 O 19 to KMnO 4 (1 : 0.25, 1 : 0.5, 1 : 0.75, and 1 : 1). The main goal of the analysis was to figure out how well the hydrothermal synthesis method worked at different temperatures (140 °C, 160 °C, and 180 °C) and holding times (9 h, 12 h, and 15 h). The composite material was subjected to characterization using a vector network analyzer, specifically at thicknesses of 1.5 mm, 2 mm, 2.5 mm, and 3 mm. The hydrothermal temperature and composition ratio of BaFe 12 O 19  : MnO 2 are the most influential parameters in reducing reflection loss. Accurate control of the parameters makes a BaFe 12 O 19 @MnO 2 core-shell composite structure with a lot of sheets. The structure is capable of absorbing 99.99% of electromagnetic waves up to a sample thickness of 1.5 mm. The novelty of this study is its ability to achieve maximal absorptions on a sample with minimal thickness through precise parametric control. This characteristic makes it highly suitable for practical applications, such as performing as an anti-radar coating material. BaFe 12 O 19 @MnO 2 demonstrates performance as a reliable electromagnetic wave absorber material with simple fabrication, producing absorption at C and X band frequencies.