On the 2H- to 3C-Type Transformation and Growth Mechanism of SiC Nanowires upon Carbothermal Reduction of Rice Straws.

SiC nanowires (NWs) and nanoparticles (NPs) fabricated by carbothermal reduction of rice straws with/without FeSi catalysts were characterized by transmission electron microscopy to study the catalyst-facilitated vapor-liquid-solid (VLS) growth against the oriented attachment of the crystals, which underwent 2H- to 3C-type transformation. The cotectic melt of the FeSi catalyst in the Fe-Si-C-O system turned out to promote the VLS growth to form straight and occasionally tapered NWs in contrast to the zigzag ones via the ()-specific coalescence of the faceted NPs. The SiC NWs showed [0001]-directed growth more or less stacked with {111} interlayers following the optimum crystallographic relationship (0001)//{111̅}; [21̅1̅0]//⟨101⟩ with zigzag {111} lateral steps and polysynthetic twins/faults near the (0001)/(111) interface.