Facile synthesis of boron carbide elongated nanostructures via a simple in situ thermal evaporation process

Boron carbide elongated nanostructures such as nanowires, nanobelts and nanosheets have been synthesized via a low-cost and simple in situ thermal evaporation process using commercially available B4C powders as the main precursor. Heat treatments were done in the temperature range of 1400-1600 °C in the presence of Co nanoparticles (and NiCl2 in some experiments) as the catalyst material. The growth mechanism of the nanostructures was proposed to be a cooperative growth procedure including surface diffusion, vapor-liquid-solid (VLS) and solid-liquid-solid (SLS) growth mechanisms. The final product, containing some of the initial B4C particles and as-synthesized elongated nanostructures may be potentially applicable as an excellent reinforcing phase in composite materials. Moreover, nanostructures with right angle junctions were obtained from the sidewalls of the graphite boats, which may be operative in MEMS and NEMS devices. The samples have been characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and photoluminescence spectroscopy.