Synthesis of photoluminescent polycrystalline SiC nanostructures via a modified molten salt shielded method

Polycrystalline SiC (3C-, 6H-, 24R- and 27H-) nanostructures are synthesized via a modified molten salt shielded synthesis method (m-MS3) in open air using Si and carbon black as the starting materials. The influences of salt species and their amount, and the sintering temperature, are discussed and optimized. Well crystalline SiC nanopowders composed of bountiful microstructures (nanoparticles, nanowires, nanosheets and nanoblocks) are successfully synthesized by m-MS3 at 1250 °C, with KCl and NaCl as the shielding salt. The polycrystalline SiC powders showed excellent photoluminescence property at an excitation wavelength of 330 nm and relatively small band gaps of 2.57–2.74 eV, which are quite attractive among reports for SiC-based materials. The investigation in this paper may provide a prototype strategy for protection-free synthesis of nanostructured SiC powders applicable for ultraviolet luminescence devices.