A design of core-shell structure for γ-MnO_2 microspheres with tunable electromagnetic wave absorption performance

摘要

Manganese dioxide (MnO_2) has been widely utilized in the electromagnetic wave (EMW) absorption feld because it exhibits numerous crystal types including α-MnO_2, β-MnO_2, γ-MnO_2, and δ-MnO_2, and is environmentally friendly. To enhance the EMW absorption performance of this material, we combined the precipitation method and calcination process to obtain γ-MnO_2 microspheres, and developed a core-shell structure of γ-MnO_2@SiO_2 and γ-MnO_2@SiO_2@TiO_2 microspheres via the sol-gel process. Based on the synergistic effects between the core-shell structure and dielectric loss, γ-MnO_2@SiO_2 with a thickness of 2.85 mm achieved the minimum refection loss of 60.2 dB, demonstrating that these microspheres are excellent candidates for EMW absorbers.