Essential role of catalyst in vapor-liquid-solid growth of compounds

The mechanism of the solidification of compound materials, such as oxide crystals, in a vapor-liquid-solid (VLS) system is investigated by model molecular dynamics simulation. A simple model for the VLS growth of a compound crystal is proposed to clarify the general mechanism of how a liquid solvent catalyzes the growth rate. We find that the nucleation process at the solid surface is responsible for limiting the growth rate, and that the solvent catalyzes the nucleation by reducing the critical nucleation size at the liquid-solid interface. Our theoretical suggestion that the ratio of the vapor-solid (VS) growth rate to the VLS growth rate strongly depends on the supply rate qualitatively agrees well with the experimental result. Finally, we simulate the entire process of VLS nanowire formation.