Electromagnetic wave absorption performance and mechanisms of geoploymer-based composites containing core-shell SiO2@Fe3O4 nanoparticles

The development of construction materials with excellent electromagnetic wave (EMW) absorbing capacity is urgently needed to ensure extensive electromagnetic radiation protection. In the present work, the geopolymer nanocomposites were prepared by introducing silica-coated Fe 3 O 4 (SiO 2 @Fe 3 O 4 ) as the EMW absorbent. The SiO 2 shell improved the dispersion of Fe 3 O 4 , leading to optimization of the electromagnetic parameters for enhancing the EMW absorbing performance. The minimum reflection loss ( RL ) reduced from - 35.7 dB to - 43.6 dB. The effective absorption bandwidth corresponding to RL lower than - 10 dB was widened from 3.6 GHz to 7.0 GHz when Fe 3 O 4 was being replaced by SiO 2 @Fe 3 O 4 . The excellent EMW absorbing performance was credited to the synergetic effect of dielectric loss and magnetic loss. The obtained absorbing performance was more competitive than other cement or geopolymer based composites, suggesting that SiO 2 @Fe 3 O 4 had high potential applications in construction building with EMW absorption.