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.