Characterization of Nickel Assisted Growth of Boron Nanostructures

Abstract

Boron nanostructures were synthesized by the vapor-liquid-solid mechanism using nickel as a catalyst. Two types of catalyst deposition methods were used: thermal evaporation and solution dispersion of Ni nanopowder. Also, the effect of synthesis temperature on the shapes of the nanostrucrure formed is reported here. The nanostructures were primarily characterized by Scanning Electron Microscopy (SEM). Further qualitative analyses were done with Transmission Electron Microscopy (TEM) and High Resolution Transmission Electron Microscopy (HRTEM). For quantitative analyses Energy Dispersive X-ray spectroscopy (EDX) and Electron Energy Loss Spectroscopy (EELS) were used. These results confirmed that 1) high purity Ni assisted boron nanostructures grow by pyrolysis of diborane, and that 2) oxide assisted growth of the nanostructures did not take place as carbon and oxygen were present only as surface contamination. Selected Area Electron Diffraction (SAED) patterns showed that the nanostructures were mainly crystalline. By decreasing the amount of nickel catalyst that is deposited by thermal evaporation the diameters of the nanowires were reduced. Also, the use of nickel nanopowder as catalyst instead of Ni film resulted in significant reduction in wire diameter. The diameter of the boron nanowires are about 36 nm. With nanowires other types of nanostructures were formed in either type of deposition. At the lower reaction temperature formation of nanosheets was observed.