Achieving Rapid Synthesis of High-Purity SiC at 1923 K via a Liquid-State Reaction

SiC devices are leading a revolution in wide-band gap semiconductors, while their high cost has restricted their rapid popularization. The first key step in preparing inexpensive SiC materials is to prepare inexpensive high-purity SiC (99.995%)─the core raw material to prepare SiC devices. The current solid-state reactions, Si(s, l) + C(s) → SiC(s) and 3C(s) + SiO2(s, l) → SiC(s) + 2CO(g), hardly achieve the requirements of low price and high purity due to the use of solid C as a reactant. Here, we report a liquid-state synthetic method for rapid preparation of high-purity (>99.996%) SiC at 1923 K by the addition of La (99.8%) to the Si–C solution formed by C (99.93%) and Si (6 N) via the desirable but generally considered impossible liquid-state reaction Si(l) + C(l) → SiC(s) at 1923 K. The C solubility in the liquid solution was significantly increased by the addition of La, realizing the replacement of solid C with liquid C in the reactants. We also propose a semicontinuous production prototype, making this new method possible for large-scale production with low cost and high efficiency.