Factors Affecting Formation of Metastable Ni3C Phase in a Solution-Based Method

Ni3C nanoparticles are synthesized over a wide range of reaction conditions by thermal decomposition of organometallic precursors in the organic solution medium. It is found that Ni3C nanoparticles are formed using Ni nanoparticles as an intermediate. The carbon component originating from the organic solution medium to enter into Ni metal lattice is identified as a diffusion-controlled reaction, which is speeded up by increasing the reaction temperature and completed by prolonging the reaction time. Any organic molecule which contains active carbon atoms is found to be a good candidate as carbon source and combine with nickel nanoparticles to form Ni3C phase. Although this paper emphasizes on the preparation of metastable Ni3C phase, at the same time, this work could effectively direct the synthesis of Ni nanoparticles in organic solution, by avoiding the formation of Ni3C phase.