Synthesis of monophase two-dimensional α-Si3N4 nanoplatelets via an ionothermal route

Monophase α-Si 3 N 4 was prepared by a salt melt strategy using Si as a starting material. The results showed that molten salt enhanced the conversion of Si to monophase α-Si 3 N 4 , and some as-synthesized α-Si 3 N 4 nanoparticles had a hexagonal platelet morphology. The α-Si 3 N 4 hexagonal nanoplatelets had an average lateral dimension of about 170 nm and a thickness of about 5.2 nm. The nitridation of Si in molten salt was investigated by a thermal quenching method, and the silicon halide intermediate products were detected by X-ray photoelectron spectroscopy. Silicon halides possessing higher reactive activity facilitated the nitridation of Si and nucleation of α-Si 3 N 4 . Furthermore, the lattice mismatch between α-Si 3 N 4 and the salts was calculated, suggesting that the lateral growth of α-Si 3 N 4 nanoplatelets had been guided by the salt crystal structure. Based on the results, the relevant formation mechanism of α-Si 3 N 4 nanoplatelets was proposed.