Doped, conductive SiO2 nanoparticles for large microwave absorption

Abstract

Although many materials have been studied for the purpose of microwave absorption, SiO2 has never been reported as a good candidate. In this study, we present for the first time that doped, microwave conductive SiO2 nanoparticles can possess an excellent microwave absorbing performance. A large microwave reflection loss (RL) of −55.09 dB can be obtained. The large microwave absorption originates mainly from electrical relaxation rather than the magnetic relaxation of the incoming microwave field. The electrical relaxation is attributed to a large electrical conductivity that is enabled by the incorporation of heterogeneous (N, C and Cl) atoms. The removal of the magnetic susceptibility only results in a negligible influence of the microwave absorption. In contrast, the removal of the heterogeneous atoms leads to a large decrease in the electrical conductivity and microwave absorption performance. Meanwhile, the microwave absorption characteristics can be largely adjusted with a change of the thickness, which provides large flexibility for various microwave absorption applications.

Influence of Nanoparticles on Thermal and Electrical Conductivity of Composites

“…SiO 2 nanoparticles are non-conductive and are associated with low microwave absorption; however-with surface modification of nitrogen, carbon, and chlorine atoms-these proved to be good conductors with excellent microwave absorptive properties [52]. When applying a nanoparticle polymer solution onto a substrate the spraying method proved to be more effective.…”

“…When heterogeneous nitrogen, carbon, and chlorine atoms were incorporated on the surface these nanoparticles proved to be effective electrical conductors with the ability to absorb microwaves because of dielectric loss due to improved electrical conductivity. This makes the particles suitable for applications such as wireless communications and anti-radar materials, even when incorporated into a suitable noninterfering matrix [52].…”

Effect of Ball Milling on the Absorption Properties of Fe3O4

“…To study the absorption of materials, reflectivity was simulated using MATLAB software, based on the electromagnetic parameters measured by a vector network analyzer. The electromagnetic wave absorption capacity was expressed by the reflection loss RL (dB) as [20]…”

Facile synthesis of a novel WO3/Ag2MoO4 particles-on-plate staggered type II heterojunction with improved visible-light photocatalytic activity in removing environmental pollutants

“…On the other hand, the staggered bandgap and intimate contact between Ag 2 MoO 4 and WO 3 greatly promote the charge separation and transfer in the Ag-W heterojunction. [52][53][54][55][56][57][58][59] Under visible light irradiation, both Ag 2 MoO 4 and WO 3 can be excited to photogenerated electronhole pairs. Since the potentials for CB and VB of Ag 2 MoO 4 are more negative than that of Ag 2 MoO 4 , photogenerated electrons in the CB of Ag 2 MoO 4 can be transferred to that of WO 3 while holes in the VB of WO 3 can be transferred to that of Ag 2 MoO 4 .…”