The origin of the strong microwave absorption in black TiO2

Abstract

In this study, the mechanism of the strong microwave absorption in black TiO2 nanoparticles has been investigated both experimentally and theoretically. In experiment, the amorphous TiO2 nanoparticles/paraffin wax composites show the reflection loss (RL) of −4.0 dB, which is much smaller compared with the RL of −49.0 dB in those core/shell structure ones. Theoretically, the calculation illustrates that the accumulated charge of 1013 cm−3 at the core/shell interface results in the plasmon resonance with the incident microwave frequency at 9.3 GHz and 27.0 GHz. The microwave absorption enhancement of the black TiO2 nanoparticles is proposed to originate from the synergy mechanism between their crystalline-cores and amorphous-shells, rather than the defects and impurities in amorphous phase.