A design of core-shell structure for γ-MnO2 microspheres with tunable electromagnetic wave absorption performance.

Manganese dioxide (MnO 2) has been widely utilized in the electromagnetic wave (EMW) absorption field 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 reflection loss of −60.2 dB, demonstrating that these microspheres are excellent candidates for EMW absorbers. [ABSTRACT FROM AUTHOR]