Vapor-solid reaction for silicon carbide hollow spherical nanocrystals

We report the synthesis of silicon carbide (SiC) hollow spherical nanocrystals using a vapor-solid reaction between carbon nanoparticles and silicon monoxide vapor generated from a mixture of silicon and silica. The hollow spherical nanocrystal diameters are related to the diameters of the pristine carbon nanoparticles, showing a shape memory effect. The thickness of the hollow spherical nanocrystals can be controlled by the siliconization degree and carbon nanoparticle multilayer structures. Different analysis techniques recorded the phase conversion of the amorphous carbon into graphitic carbon in the structure of the sp² bond state and further into SiC nanocrystal in the structure of the sp³ diamond-like carbon bond state. The hollow spherical nanocrystals might find applications in catalysis, controlled delivery, gas storage, low-dielectric nanomaterials, acoustic insulation, and nanocomposites.