Synthesis of monophase two‐dimensional α‐Si ₃ N ₄ nanoplatelets via an ionothermal route

Abstract 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.