Synthesis, Magnetic and Electromagnetic Absorption Properties of Amorphous Core-Shell Fe-B@SiO2 Submicrospheres

Amorphous core-shell Fe-B@SiO₂ submicrospheres with the SiO₂ shell layer of about 18 nm were fabricated via a two-step process. Fe-B submicrospheres were first obtained, and core-shell Fe-B@SiO₂ submicrospheres were subsequently fabricated using TEOs as a Si source through a modified Stöber method. The measurements of the magnetic properties demonstrated that the amorphous core-shell Fe-B@SiO₂ submicrospheres exhibit ferromagnetic behavior at room temperature. The maximum reflection loss reaches −24.8 dB at 11.76 GHz for the absorber with thickness of 2.2 mm. The absorption bandwidth with the reflection loss below −10 dB is up to 14.76 GHz for the absorber with a thickness of 1.5-6 mm and the absorption bandwidth with the reflection loss below −20 dB is up to 6.6 GHz for the absorber with a thickness of 1.8-3.1 mm. Our results demonstrates that the amorphous core-shell Fe-B@SiO₂ submicrospheres obtained in this work are attractive candidate materials for the magnetic and EM wave absorption applications.