Modification of plasma-generated SiC nanoparticles by heat treatment under air atmosphere

Plasma-generated SiC nanoparticles are easily functionalized due to their ability to be easily oxidized. In this study, SiC nanoparticles were synthesized in non-thermal arc plasmas via hexamethyldisilane decomposition, and the products were modified by heat treatment under air atmosphere. Results indicated that the plasma-generated SiC nanoparticles were C-coated SiC nanoparticles with an average size of 8 nm, while the heat treatment transformed the initial carbon coating layers into SiO2 layers to form SiO2-coated SiC nanoparticles by surface oxidation. The formation of SiO2 layers enhanced the photoluminescence performance in the blue-green emission region, and also resulted in a blue-shift in the photoluminescence peak mainly due to the surface/defect states. The C-coated SiC nanoparticles exhibited excellent microwave absorption ability, and the optimal reflection loss approached -38.4 dB at 11.7 GHz under an absorber thickness of 2.0 mm; however the formation of SiO2 layers after modification decreased the conduction loss of SiC nanoparticles, thus weakening their microwave absorption. These results afford a new strategy for designing and synthesizing C/SiO2-coated SiC nanoparticles. (C) 2021 Elsevier B.V. All rights reserved.