Tunable Synthesis of SiC/SiO₂ Heterojunctions via Temperature Modulation.

A large-scale production of necklace-like SiC/SiO₂ heterojunctions was obtained by a molten salt-mediated chemical vapor reaction technique without a metallic catalyst or flowing gas. The effect of the firing temperature on the evolution of the phase composition, microstructure, and morphology of the SiC/SiO₂ heterojunctions was studied. The necklace-like SiC/SiO₂ nanochains, several centimeters in length, were composed of SiC/SiO₂ core-shell chains and amorphous SiO₂ beans. The morphologies of the as-prepared products could be tuned by adjusting the firing temperature. In fact, the diameter of the SiO₂ beans decreased, whereas the diameter of the SiC fibers and the thickness of the SiO₂ shell increased as the temperature increased. The growth mechanism of the necklace-like structure was controlled by the vapor-solid growth procedure and the modulation procedure via a molten salt-mediated chemical vapor reaction process.