Growth of Dual DLC and Icosahedral Boron Carbide Nano-Crystals by HFCVD

Abstract

Carbon nano-structures were doped by boron atoms to synthesize icosahedral boron carbide using Hot Filament Chemical Vapor Deposition method. Raman spectroscopy revealed two broad peaks centered on 1,334 and 1,573 cm−1, the origin of which is sp3 hybrid of diamond (D-band) and sp2 hybrid of graphite (G-band), respectively. These peaks stem from aromatic compounds with sp2 hybrid, demonstrating a local collection of amorphous B13C2 on the substrate surface. Furthermore, D and G peaks are illustrative of more damage inside the structure. X-ray diffraction patterns indicated significant peaks assigned to icosahedral (B13C2) structures in planes (012), (021), and (024). Debye–Scherrer calculation showed that, the crystal size of the products was in range of 5–80 nm. Additionally, the graphite grain size was evaluated by Tuinstra–Koenig formula at a 42–73 nm interval. The decrease observed in the intensity of G and D peaks may stem from disrupting the vibrational behavior of the film and diminution of polarizability in the molecules of the lattice. One of the factors inducing the decrease of polarizability the promotion of is a great fraction of δ bonds between B-C atoms. Scanning electron microscopy results showed cauliflowers morphology for the nanostructures.