Synthesis of silicon carbide nanoparticles from amorphous carbon: Based on the domain structure of electrically calcined anthracite

Abstract

Based on the domain theory, the domain structure of electrically calcined anthracite was studied for the first time. The carbon microstructure of the electrically calcined anthracite was analyzed using atomic force microscopy (AFM). The analysis revealed that the carbon microstructure comprised microdomains with particle sizes below 30 nm and domains with particle sizes below 200 nm. In addition, non-graphitizable carbon structures formed by partial microdomain and domain structures were difficult to grow. Thus, we successfully synthesized novel β-type silicon carbide (β-SiC) nanoparticles with larger particle sizes below 200 nm and smaller particle sizes below 60 nm using a non-graphitizable carbon composed of carbon nanoparticles as the main raw material. Through calculation and analysis, the synthesis mechanism revealed that due to the presence of highly reactive interfacial regions between the domains of electrically calcined anthracite, silicon first diffused to the highly reactive interface between the domains of electrically calcined anthracite and reacted with the highly active carbon atoms in it to form silicon carbide, resulting in a certain degree of volume expansion. The volume expansion led to the cracking and dispersion of the domains, which further led to mutual diffusion and reaction within the exfoliated domains to generate SiC nanoparticles. And the non-exfoliated SiC nanoparticles generated at the reaction interface on the surface of electrically calcined anthracite were observed by the AFM.